This patch is part of the community goals to enable python 3 first, and
only use python 2 when explict.
To do so, this patch:
- Makes python 3 the default env for non py27 tox targets.
- Adds a py3-dev target for running py3 locally.
- Refactors the pip install commands for stable dependency install into
their own target and refs them where needed.
- Updates the code to pass pep8 in python 3.
- Bumps the version of pylint to 1.7.1 to address some py3 issues in
earlier versions.
As part of this effort we should also look into making python 3 the
default for our VMware NSX 3rd party CI jobs.
Change-Id: Ibaa3e9d717f32ffb6479346163c14d4be7df50cf
2633ec0607