Issue #13 verify_redirection_uri improvements
Separated scope verification in oauth2_backend:verify_client_scope/2 and
oauth2:verify_user_scope/2 (Issue #12)
Merge branch 'master' of https://github.com/IvanMartinez/oauth2

Conflicts:
	src/oauth2.erl
	src/oauth2_backend.erl
	test/oauth2_tests.erl