Automate installation of dependencies on Ubuntu 14.04.

'make deps' now installs GL header files required to compile Rabbyt
(compile happens during pip install.)

Makefile now explicitly contains bash commands, not default of /bin/sh.

requirements are now specifiec in setup.py, and referenced from
requirements.txt using "-e .". This means that installing deps
using "pip install -r requirements.txt" will also install executable
script hooks in virtualen/bin, like the one 'tanks', that runs the game.

Delete setup.py reference to argparse.
Where we're going, we don't need argparse.

Add README 'To Do' section.
rename everything tanks->zerkcom