Remove some unused variables and imports.
Fix up run, list, kill commands and add submit (previously deploy) command.

This is a large commit that probably should've been broken into much smaller ones (sorry about that).  Will try to summarize the changes:

1) Modify the docopt string for sparse to have commands: quickstart, run, submit, list and kill.
2) For commands that require a topology name and definition file, intelligently figure one out if it wasn't specified from command line.
3) For commands that require an environment config, intelligently figure out one if it wasn't specified from command line.
4) Add the submit command which does lots of magic (best to check submit_topology in invoke.py).

Addresses issues: #1 #4 #5.