Cache site-packages between tests
Fix .travis.yml
Use latest gevent
PEP8 whitespace fixes
More PEP8 fixes
Fix import
Merge remote-tracking branch 'origin/retry-if-missing-packages'

Conflicts:
	yaybu/provisioner/providers/apt.py
More PEP8 fixes
Flake8 fixes
Update release notes
Bump yay dependency
Preparing release 3.1
Back to development: 3.2