rearranging code into a proper python package, per #1
switching to relative imports, plus other minor improvements based on review.
replacing run.sh with a "docker-registry" console script
fixing package name to use a - instead of _, and improving a doc block.
Merge branch 'python-packaging' of github.com:mhrivnak/docker-registry into mhrivnak-python-packaging

Conflicts:
	docker_registry/app.py
	docker_registry/images.py
	registry/__init__.py
	run.sh
	test/base.py
Fixed imports and paths