Add an access control module The module's purpose is to check access requirements, (such as being logged in), and raise an exception containing a authentication request when the requirement is not met. Patch by: Sverre Rabbelier Reviewed by: Pawel Solyga, Augie Fackler, Todd Larsen Reviewed at: http://codereviews.googleopensourceprograms.com/1601 Review id: 1601