Cloning (& Building) of Dependencies

[romanb]

Atm. the dependencies in the Intfile are specified as git URLs which Keiretsu clones and builds. It might be better (or at least an alternative) to specify paths to the dependencies instead. Otherwise with the current scheme it would need to recursively clone and build dependencies, including taking care of cycles, which it doesn't do yet and leads to a lot of redundant clones and builds.