Update repository after OpenStack migration

* Add .gitignore
* Update .gitreview (we thought it would be on Stackforge, but finally
  it's on OpenStack)
* Add .testr.conf
* Update run-flake8 script to avoid error when running flake8 without
  elements.
* Update setup.cfg with correct name & description
* Add no_dup_filenames unit test (required to have py27 gate working)

Change-Id: Iea79eb5ccaa5ea765730ca99e146e54a3c0812f9