Use string filter instead of record for location_type

`active_interaction` doesn't coerce an empty string value to the default
value on `record` filters[1]. This causes the form to break on any form
where `location_type` is optional (eg CommunityResources#create).

We hadn't run into this on the Ask|Offer form because we only show the
location_type input once the user provides an address, and then rely on
the browser to enforce that it's populated.

[1] AaronLasseigne/active_interaction#503

app/forms/location_form.rb

@@ -3,7 +3,7 @@
 class LocationForm < BaseForm
   with_options default: nil do
     integer :id
-    record  :location_type
+    integer :location_type
     string  :street_address
     string  :neighborhood
     string  :city
@@ -17,7 +17,14 @@ def execute
     return nil if inputs.values.all?(&:blank?)
 
     Location.find_or_new(id).tap do |location|
-      location.attributes = given_inputs
+      location.attributes = given_inputs_without_location_type
+      location.location_type_id = location_type if given?(:location_type)
     end
   end
+
+  private
+
+    def given_inputs_without_location_type
+      given_inputs.reject {|key| key == :location_type }
+    end
 end

spec/forms/submission_form_spec.rb

@@ -89,6 +89,7 @@
           before do
             params[:location_attributes] = {
               street_address: '',
+              location_type: '',
             }
           end