Add module for deprecating model attributes
Add module for deprecating model attributes

This will cause a deprecation message to be logged when any attribute
related method (Model#foo, Model#foo= and Model#foo?) is used.

unboxed/e-petitions,alphagov/e-petitions,StatesOfJersey/e-petitions,StatesOfJersey/e-petitions,joelanman/e-petitions,joelanman/e-petitions,alphagov/e-petitions,unboxed/e-petitions,StatesOfJersey/e-petitions,oskarpearson/e-petitions,unboxed/e-petitions,StatesOfJersey/e-petitions,oskarpearson/e-petitions,oskarpearson/e-petitions,alphagov/e-petitions,joelanman/e-petitions,unboxed/e-petitions,alphagov/e-petitions