Remove deprecated attributes from Widget::Card

Some fields from Widget::Card are translatable and we no longer need
them. This commit will remove the annoying deprecation warning thrown
by Globalize gem after gem version update.

db/migrate/20190221172209_remove_deprecated_translatable_fields_from_widget_cards.rb

@@ -0,0 +1,8 @@
+class RemoveDeprecatedTranslatableFieldsFromWidgetCards < ActiveRecord::Migration[4.2]
+  def change
+    remove_column :widget_cards, :label, :string
+    remove_column :widget_cards, :title, :string
+    remove_column :widget_cards, :description, :text
+    remove_column :widget_cards, :link_text, :string
+  end
+end

db/schema.rb

@@ -1677,11 +1677,7 @@ ActiveRecord::Schema.define(version: 20190607160900) do
   end
 
   create_table "widget_cards", force: :cascade do |t|
-    t.string   "title"
-    t.text     "description"
-    t.string   "link_text"
     t.string   "link_url"
-    t.string   "label"
     t.boolean  "header",                     default: false
     t.datetime "created_at",                                 null: false
     t.datetime "updated_at",                                 null: false