Rather than clobber the user_model class variable every time a SQL authenticator is used, use a hash to map auth_index to the associated user model.
Improve Daniel's work and move stringify_keys to lib/casserver/authenticators/base.rb.
This commit moves the logic for matching users in the sql authlogic authenticator into a separate method for extensibility. This will allow for a custom authenticator to inherit the sql authlogic class and override the matching users method with a custom query.
Very good explanation why we should not have it: http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/