Add frozen_string_literal to HipChat files

config/initializers/hipchat_client_patch.rb

+# frozen_string_literal: true
 # This monkey patches the HTTParty used in https://github.com/hipchat/hipchat-rb.
 module HipChat
   class Client

spec/features/projects/services/user_activates_hipchat_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'User activates HipChat' do

spec/models/project_services/hipchat_service_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe HipchatService do