Add a setup.cfg and setup.py and fill in those files
so that gertty can be installed easily.
Adjust gertty.py to have a main function that
can be referenced as a console entrypoint during
installation.
Also adjusted a bunch of imports that were failing after
installation occurred (but now they should not fail since they
correctly reference the gertty module namespace).
Change-Id: I532ced51583b26300ba9a2efb97f8e41bc69ec8d
Joshua Harlow