This commit is a follow-up of "switch to using stestr"
which was merged already .
After switch to using stestr, testrepository is unnecessary
and should be removed.
Recent update brought os-testr 1.0.0 that already uses stestr test
runner instead of testrepository. This patch migrates those places
using testrepository to using stestr.
Inspired by the patch of the same name in openstack/ironic
If you run tox -epep8 an .eggs file will be generated and currently it's
being tracked by the python-lib git repo, which is annoying. This patch
is adding the .eggs to the .gitignore file to avoid it.