Replace update.sh functionality

Currently we internally use a couple shell scripts to parse arguments and make sure a copy of ```ceph-qa-suite``` are checkout out before we run ```teuthology-suite```. That always seemed brittle and, more importantly, not fair to the community since those tools were kept out-of-tree. This PR adds the same functionality to teuthology itself.
if someone is using this with `sudo` this will expand to `/root/src` I take it we never do `sudo` here?