Merge pull request #7 from stv0g/master

Added support for bare repositories, additional git arguments and path suffixes
Update README.markdown

Document new arguments
update_repo must use os.chdir().  calling os.system(cd
Merge pull request #8 from dougt/use_chdir_not_cd

update_repo must use os.chdir().  calling os.system(cd
bugfix: do not alter objects, as these changes are global