Wrap as a CinderBlock

Until this matures and can be discussed for inclusion into Cinder core, I think it will be a lot easier to get feedback if the project is structured as a CinderBlock. This adds a simple cinderblock definition and tweaks the project files to fit - namely `CINDER_PATH` and the *Blocks* group.

This does *not* change the iOS Xcode projects as they aren't setup yet and it also doesn't do anything to the in-progress capture work which doesn't compile if included. As an aside, the existing AV Foundation capture used for iOS can also be used for OS X, so that might be an option as well..