initial set of changes to get LW working in the Biba environment

* `app_name` is a class method
* fix Resque `defined?` check - when the symbol wasn't fully qualified it was being mistaken for LogWeasel::Resque under ree
* pin ActiveSupport dependency to ~3.2 - 4.0 requires ruby 1.9.3
* ignore .rvmrc - environment-specific config files shouldn't be checked in for libraries

@newcolabs/rails-developers