pep8
Add bin script for testing.

Testing gitifyhg is difficult when there's an installed egg version: eggs
are placed on sys.path ahead of anything in PYTHONPATH.  This commit adds
a bin script that puts a source-code gitifyhg on sys.path ahead of
everything else, so it can be tested.  It is NOT intended that this replace
the bin script installed by setup.py; it is only for testing.  With this
script, I can say:
PATH=/path/to/gitifyhg/bin git ...
and get the version of gitifyhg in /path/to/gitifyhg/gitifyhg.
To ensure this bin script isn't used unintentionally, it's named
git-remote-testgitifyhg, so you have to also have a remote called:
testgitifyhg::<mercurial/repo>
i.e., you can have separate production and development gitifyhg remotes.
move Paul's testgitifyhg script into the t directory.

The script can still be used manually from this directory, but in my mind, its primary purpose will be to be called by
the sharness tests. This should ease the problem of the test harness picking the system gitifyhg even when a venv is
activated.
For now, I want to start afresh instead of using these tests from remote-hg.
I want to ensure every test in the gitifyhg py.test library is represented in sharness.
the env vars are probably only needed by the reference tests
This readme info has been included into the main readme.
Add the first sharness test ported from py.test.

This was a lot more work than I expected, but I think I'm getting the hang of it. A lot of
the bootstrap code used in py.test (eg: setting up environment variables, configs, and usernames
is being neglected here. I'll add them back as I port remaining tests.