Changed generators to allow multiple user classes

(cherry picked from commit 8d16138956ee08acf2990fc6e5391b0fe9257b78)
Added 'any instance' capability to User.with_role

(cherry picked from commit b90594fd5e64d9d954c50e54777e7a3f6949707b)

Conflicts:
	lib/rolify/finders.rb