Issue #13 verify_redirection_uri improvements
Tests updated. Minor fixes.
Merge branch 'issue_13_verify_redirection_uri' of git://github.com/IvanMartinez/oauth2 into IvanMartinez-issue_13_verify_redirection_uri
Change oauth2_backend to a behavior
Merge branch 'IvanMartinez-issue_13_verify_redirection_uri'

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