Add prepend_methods to ActiveSupport::Concern

[Philippe Van Eerdenbrugghe]

I often find myself needing to prepend some methods in a concern in order to be able to use a macro and override the generated methods with some twists.

I usually do something like this https://gist.github.com/Systho/0bc4b9236abb039fbdb4 because it's easy to read and understand.

I would find it very useful to have it directly available in ActiveSupport::Concern and I'm ready to write some code and tests for this feature if I'm not the only one interested.

What do you think of it ?