Fixed broken parentPath Implementation #22, #23

The code was pretty hard to follow but since I really wanted to get some generators going I had no choice but to dig through it.

One change needs to happen to `generator.json` files: if dependency has `{{parentPath}}` the generator needs to have ``parentPath`` key set to the default parent path. This is the only way I could fix #22.

Previous behavior is unaffected (as far as I could debug, but who knows with no tests, :+1: for #13.) I'm unsure whether or not it breaks other things but upon inspection it does not appear to do so.  If possible I'd love  a version bump for `npm`.

fixes #22, #23.