Add a controller hooking feature

[estum]

Allow to define a hook in initializer, which invokes the controller class. This useful when we need to set some custom callbacks.

Usage exaple (adding basic auth):

# config/initializers/api_taster.rb

ApiTaster.controller_hook do
  http_basic_authenticate_with name: "admin", password: "123456"
end

[fredwu]

This is a great feature to have! Though as it stands it breaks the build, and please add some tests to cover this new feature too. :)