Misc fixes to stuff found while debugging / working on salt-ssh:

UPDATED: after rebase: removed pre-existing salt/modules/iptables.py fix as it's already upstream...

- SUDO command string/logic for salt-ssh fixed
- command & args (list) now passed to Single properly/as it expects w.r.t. current implementation (vs. one big string)
- added absolute imports to utils/thin.py - this does not break any existing imports untouched, but fixes case where extra mods are being included with "salt-run thin.generate", as mako (as an example) will not be imported properly without absolute imports since there exists a mako.py file inside the utils/ dir, etc.
- also added "backports" module to thin tar generation, since it is required by other stuff in the core "thin" modules in some setups