Merge pull request #180 from azul/feature/messages-api

app/controllers/controller_extension/json_responses.rb

app/controllers/v1/messages_controller.rb

app/models/message.rb

app/models/user.rb

config/initializers/add_controller_methods.rb

config/locales/errors.en.yml

config/locales/messages.en.yml

features/messages.feature

features/step_definitions/api_steps.rb

features/step_definitions/messages_steps.rb

features/support/hooks.rb

test/factories.rb

test/functional/v1/messages_controller_test.rb

test/support/assert_responses.rb