nova: fixes units tests failures when run using rpm

Was missing a critical step - python setup.py egg_info. This patch also fixes
the way git repo was cleaned. It now uses git clean -qdffx to cleanup.

Running tests in virtualenv uses (almost) the same command as running it with
rpm packages.

Change-Id: I8523af84c11413146bac3c34e736f93324f7985e