Admin Users require role

These changes make the role field required in the User model. Changes to
the Admin user edit view were added to provide validation for the role
field.

As an added enhancement, the user's roles are displayed in the Admin
user list view.

modules/users/client/views/admin/edit-user.client.view.html

@@ -7,22 +7,25 @@ <h1>User <span ng-bind="user.username"></span></h1>
       <fieldset>
         <div class="form-group" show-errors>
           <label for="firstName">First Name</label>
-          <input type="text" id="firstName" name="firstName" class="form-control" ng-model="user.firstName" placeholder="First Name" required>
+          <input type="text" id="firstName" name="firstName" class="form-control" ng-model="user.firstName" placeholder="First Name" required />
           <div ng-messages="userForm.firstName.$error" role="alert">
             <p class="help-block error-text" ng-message="required">First name is required.</p>
           </div>
         </div>
         <div class="form-group" show-errors>
           <label for="lastName">Last Name</label>
-          <input type="text" id="lastName" name="lastName" class="form-control" ng-model="user.lastName" placeholder="Last Name" required>
+          <input type="text" id="lastName" name="lastName" class="form-control" ng-model="user.lastName" placeholder="Last Name" required />
           <div ng-messages="userForm.lastName.$error" role="alert">
             <p class="help-block error-text" ng-message="required">Last name is required.</p>
           </div>
         </div>
-        <div class="form-group">
+        <div class="form-group" show-errors>
           <label class="control-label" for="roles">Roles</label>
           <div class="controls">
-            <input class="form-control" type="text" name="roles" ng-model="user.roles" id="roles" ng-list />
+            <input class="form-control" type="text" name="roles" ng-model="user.roles" id="roles" ng-list required />
+            <div ng-messages="userForm.roles.$error" role="alert">
+              <p class="help-block error-text" ng-message="required">At least one role is required.</p>
+            </div>
           </div>
         </div>
         <div class="form-group">

modules/users/client/views/admin/list-users.client.view.html

@@ -12,6 +12,7 @@ <h1>Users</h1>
   <div class="list-group">
     <a ng-repeat="user in pagedItems" ui-sref="admin.user({userId: user._id})" class="list-group-item">
       <h4 class="list-group-item-heading" ng-bind="user.username"></h4>
+      <p class="list-group-item-text pull-right small" ng-bind="user.roles"></p>
       <p class="list-group-item-text" ng-bind="user.email"></p>
     </a>
   </div>

modules/users/server/models/user.server.model.js

@@ -85,7 +85,8 @@ var UserSchema = new Schema({
       type: String,
       enum: ['user', 'admin']
     }],
-    default: ['user']
+    default: ['user'],
+    required: 'Please provide at least one role'
   },
   updated: {
     type: Date