Added .rb to migrations
Updated travis settings to specific rails version
Added 'any instance' capability to User.with_role

(cherry picked from commit b90594fd5e64d9d954c50e54777e7a3f6949707b)

Conflicts:
	lib/rolify/finders.rb
Changed generators to allow multiple user classes

(cherry picked from commit 4f7c0f9efa5cf6c3146d427612efd8e1bcd2961e)
Fixed tests for differentiated adapters