Changes for initial push with tests

This is the foundation of the backup script for Yelp's Bower Postgres backup.  The script currently verifies packages in the package directory and has templates for syncing remote and local files.  No postgres functionality has currently been implemented.  Currently code in main shows functionality of functions.
Please don't os.system.
If you must, use subprocess.Popen.
I don't quite see what you're testing here tho.
Are you asserting that all the git urls are valid? I'm not sure that's a contract of this package.