Migrate fabricators to factory bot factories (#626)

* Remove factory_girl include from dev rake task

No longer needed after 92b125b4a7

* Add missing factories

* Use FactoryBot factories instead of fabricators

* Remove all fabricators

* Remove unused method

* Remove fabrication gem

* Rename FactoryGirl to FactoryBot

https://robots.thoughtbot.com/factory_bot

spec/models/message_spec.rb

@@ -20,7 +20,7 @@ describe Message do
 
   context 'with valid attributes' do
     before :all do
-      @mssage = Fabricate(:message)
+      @mssage = create(:message)
     end
 
     it 'should be valid' do
@@ -29,7 +29,7 @@ describe Message do
     end
 
     it 'should be valid twice' do
-      @mssage = Fabricate(:message)
+      @mssage = create(:message)
       @mssage.valid?
       @mssage.errors.full_messages.should match_array([])
     end