Add integration test option to tox

Take current version of hacking and run it on any
review.openstack.org repository. By default nova is used
  tox -eintegration
but you can pass in any project as an argument. For example:
  tox -eintegration -- openstack keystone

This deletes the project repo after the test.

Partially fixes bug 1186421

Change-Id: I796b7c734459042b1a929afb73434cba62477365
Merge "Add integration test option to tox"