grack 0.1.0

This project aims to replace the builtin git-http-backend CGI handler distributed with C Git with a Rack application. By default, Grack uses calls to git on the system to implement Smart HTTP. Since the git-http-backend is really just a simple wrapper for the upload-pack and receive-pack processes with the '--stateless-rpc' option, this does not actually re-implement very much. However, it is possible to use a different backend by specifying a different Adapter.