Hide controller methods from documentation

[davidcollie]

Reasons for feature and a description of the functionality described in issue #355

Example:

api :GET, '/users/see_another', 'Boring hidden method that we do not want clients to know about yet'
show false
see 'development#users#create'
see 'development#users#index', "very interesting method reference"
desc 'This method is boring, look at users#create.  It is hidden from documentation.'
def see_another
  render :text => 'This is very similar to create action'
end

[davidcollie]

I had to merge in PR #350 for testing purposes.

I can refactor the DSL name from show to something else if there is a strong objection to that name.

[iNecas]

It seems nobody objects on the name. Mergning now. Thanks @davidcollie