This automates the manual dance around version numbers for less maintenance pain.
The main visible changes are:
- requirements are in requirements.txt for now
- tags must be just x.y.z not testtools-x.y.z
- version information in __init__ is dynamically looked up.
- we can probably cleanup a bunch of our bootstrap import glue but in
the interest of clear reviews, and avoiding surprises, I'm leaving
that alone for now.
Change-Id: Ia54f681b50764a94ada68a6b2ac1bc77bfb619c5
915b2b604c