Generate AUTHORS using git log

This is a work in progress for creating the ability to easily generate an ``AUTHORS`` file using the output of ``git log``.

#### TODO
- [x] Complete and Verify the ``.mailmap`` to ensure we are accurately capturing all the names
- [x] Audit the diff to ensure that we've not lost any names
- [x] Figure out what to do with ``"Aziz Köksal"`` who is the creator of the tests/lib/path.py file but never actually contributed directly to pip but allowed the file to be relicensed.
- [x] Figure out what to do with ``"unknown <hakaton@Anam-mbl.(none)>"`` who authored 8ebc7a316016c4eb01cb77c8df1fe538c7bddf2a.