Build/Test harness with dockerfile and makefile

Signed-off-by: Erik Hollensbe <erik@docker.com>
Signed-off-by: Solomon Hykes <solomon@docker.com>
Project housekeeping

Update Dockerfile to use @tiborvass fork of libgit2.

Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>
Change Scope semantic by allowing chaining

Chaining scopes is now possible in such way that
`root.Scope("a").Scope("b").Set("foo=bar") now creates key "a/b/foo".

Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>
Merge pull request #12 from icecrime/docker_extensions_fixes

Ease development, change db.Scope() semantic