Add administrate

```
$ rails generate administrate:install

Running via Spring preloader in process 30795
       route  namespace :admin do
    resources :blogs

    root to: "blogs#index"
  end
WARNING: Unable to generate a dashboard for PaperTrail::Version.
         Administrate does not yet support namespaced models.
      create  app/controllers/admin/application_controller.rb
      create  app/dashboards/blog_dashboard.rb
      create  app/controllers/admin/blogs_controller.rb
```

Gemfile

@@ -62,3 +62,5 @@ end
 gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
 
 gem "paper_trail", "~> 10.2"
+
+gem "administrate", "~> 0.11.0"

Gemfile.lock

@@ -44,9 +44,22 @@ GEM
       tzinfo (~> 1.1)
     addressable (2.6.0)
       public_suffix (>= 2.0.2, < 4.0)
+    administrate (0.11.0)
+      actionpack (>= 4.2, < 6.0)
+      actionview (>= 4.2, < 6.0)
+      activerecord (>= 4.2, < 6.0)
+      autoprefixer-rails (>= 6.0)
+      datetime_picker_rails (~> 0.0.7)
+      jquery-rails (>= 4.0)
+      kaminari (>= 1.0)
+      momentjs-rails (~> 2.8)
+      sass-rails (~> 5.0)
+      selectize-rails (~> 0.6)
     archive-zip (0.12.0)
       io-like (~> 0.3.0)
     arel (9.0.0)
+    autoprefixer-rails (9.5.0)
+      execjs
     bindex (0.6.0)
     bootsnap (1.4.2)
       msgpack (~> 1.0)
@@ -74,6 +87,8 @@ GEM
     coffee-script-source (1.12.2)
     concurrent-ruby (1.1.5)
     crass (1.0.4)
+    datetime_picker_rails (0.0.7)
+      momentjs-rails (>= 2.8.1)
     erubi (1.8.0)
     execjs (2.7.0)
     ffi (1.10.0)
@@ -85,6 +100,22 @@ GEM
     jbuilder (2.8.0)
       activesupport (>= 4.2.0)
       multi_json (>= 1.2)
+    jquery-rails (4.3.3)
+      rails-dom-testing (>= 1, < 3)
+      railties (>= 4.2.0)
+      thor (>= 0.14, < 2.0)
+    kaminari (1.1.1)
+      activesupport (>= 4.1.0)
+      kaminari-actionview (= 1.1.1)
+      kaminari-activerecord (= 1.1.1)
+      kaminari-core (= 1.1.1)
+    kaminari-actionview (1.1.1)
+      actionview
+      kaminari-core (= 1.1.1)
+    kaminari-activerecord (1.1.1)
+      activerecord
+      kaminari-core (= 1.1.1)
+    kaminari-core (1.1.1)
     listen (3.1.5)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
@@ -101,6 +132,8 @@ GEM
     mini_mime (1.0.1)
     mini_portile2 (2.4.0)
     minitest (5.11.3)
+    momentjs-rails (2.20.1)
+      railties (>= 3.1)
     msgpack (1.2.9)
     multi_json (1.13.1)
     nio4r (2.3.1)
@@ -158,6 +191,7 @@ GEM
       sprockets (>= 2.8, < 4.0)
       sprockets-rails (>= 2.0, < 4.0)
       tilt (>= 1.1, < 3)
+    selectize-rails (0.12.6)
     selenium-webdriver (3.141.0)
       childprocess (~> 0.5)
       rubyzip (~> 1.2, >= 1.2.2)
@@ -199,6 +233,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  administrate (~> 0.11.0)
   bootsnap (>= 1.1.0)
   byebug
   capybara (>= 2.15)

app/controllers/admin/application_controller.rb

@@ -0,0 +1,21 @@
+# All Administrate controllers inherit from this `Admin::ApplicationController`,
+# making it the ideal place to put authentication logic or other
+# before_actions.
+#
+# If you want to add pagination or other controller-level concerns,
+# you're free to overwrite the RESTful controller actions.
+module Admin
+  class ApplicationController < Administrate::ApplicationController
+    before_action :authenticate_admin
+
+    def authenticate_admin
+      # TODO Add authentication logic here.
+    end
+
+    # Override this value to specify the number of elements to display at a time
+    # on index pages. Defaults to 20.
+    # def records_per_page
+    #   params[:per_page] || 20
+    # end
+  end
+end

app/controllers/admin/blogs_controller.rb

@@ -0,0 +1,21 @@
+module Admin
+  class BlogsController < Admin::ApplicationController
+    # To customize the behavior of this controller,
+    # you can overwrite any of the RESTful actions. For example:
+    #
+    # def index
+    #   super
+    #   @resources = Blog.
+    #     page(params[:page]).
+    #     per(10)
+    # end
+
+    # Define a custom finder by overriding the `find_resource` method:
+    # def find_resource(param)
+    #   Blog.find_by!(slug: param)
+    # end
+
+    # See https://administrate-prototype.herokuapp.com/customizing_controller_actions
+    # for more information
+  end
+end

app/dashboards/blog_dashboard.rb

@@ -0,0 +1,57 @@
+require "administrate/base_dashboard"
+
+class BlogDashboard < Administrate::BaseDashboard
+  # ATTRIBUTE_TYPES
+  # a hash that describes the type of each of the model's fields.
+  #
+  # Each different type represents an Administrate::Field object,
+  # which determines how the attribute is displayed
+  # on pages throughout the dashboard.
+  ATTRIBUTE_TYPES = {
+    versions: Field::HasMany.with_options(class_name: "PaperTrail::Version"),
+    id: Field::Number,
+    title: Field::String,
+    body: Field::Text,
+    created_at: Field::DateTime,
+    updated_at: Field::DateTime,
+  }.freeze
+
+  # COLLECTION_ATTRIBUTES
+  # an array of attributes that will be displayed on the model's index page.
+  #
+  # By default, it's limited to four items to reduce clutter on index pages.
+  # Feel free to add, remove, or rearrange items.
+  COLLECTION_ATTRIBUTES = [
+    :versions,
+    :id,
+    :title,
+    :body,
+  ].freeze
+
+  # SHOW_PAGE_ATTRIBUTES
+  # an array of attributes that will be displayed on the model's show page.
+  SHOW_PAGE_ATTRIBUTES = [
+    :versions,
+    :id,
+    :title,
+    :body,
+    :created_at,
+    :updated_at,
+  ].freeze
+
+  # FORM_ATTRIBUTES
+  # an array of attributes that will be displayed
+  # on the model's form (`new` and `edit`) pages.
+  FORM_ATTRIBUTES = [
+    :versions,
+    :title,
+    :body,
+  ].freeze
+
+  # Overwrite this method to customize how blogs are displayed
+  # across all pages of the admin dashboard.
+  #
+  # def display_resource(blog)
+  #   "Blog ##{blog.id}"
+  # end
+end

config/routes.rb

@@ -1,4 +1,9 @@
 Rails.application.routes.draw do
+  namespace :admin do
+    resources :blogs
+
+    root to: "blogs#index"
+  end
   resources :blogs
   # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
 end