Default to Python 3

In support of #8.

Right now I've just installed it and I'm trying to understand the right way to default to python3. There is the option of symlinking both `python` and `pip`.
Yessir. I took the get-pip installation from @ogrisel's setup. I'm not a fan of `curl`'ing scripts for installs, but reasonably trusting of the PYPA.