ging/mailboxer — pull request #207 by apneadiving (2013-10-18 14:52:52+00:00)
Title: rename module to avoid collision when subclasses inherits from AR::Base

I had:
```ruby
class User < ActiveRecord::Base
acts_as_messageable

class Profile < ActiveRecord::Base
end
end
```
Resulting in `uninitialized constant Mailboxer::Models::Messageable::ActiveRecord::Base` because ActiveRecord exists in the first ancestor: `Mailboxer::Models::Messageable`

I could have done `class Profile < ::ActiveRecord::Base` but well...