inital commit
large refactor + massive cleanup
make diffbundler work when there are no changes to the refs
properly store HEAD
fix bug that would cause no initial refs bundle to be created
make sure that we are in the right place when taring stuff up
remove path and read_only attributes that are not used
initialize _bundles attribute only when needed
added SelfCleaningTempDir helper class
add copyright and README
use argparse to parse the command line
make sure to always include the sha1 of HEAD