Warnings

@strob datasync.py is untested. Right now, code assumes that it can do a git pull, which is not happening, because i am in branch warnings, as opposed to master. Will try and merge with master locally, test, and put a comment here regardless of outcome. but wanted to issue a pull request even before that, in case you have time. I haven't played with datasync as much as you have, so if you can verify that i didn't break anything and merge, would be great. if not, i'll try to do a little bit more and comment, as mentioned before.

note that you'll have to run npm install docopt; sorry for the dependency. its small, but seems nice and clean (and worth a look for other cli, its a cross-language spec!).