Update tests in stable/havana

- keystone.test has been removed, so we need to use keystone.tests
  instead.
- Added unittest for user already in tenant
- PEP8 changes
Style and minor sintax changes

Comply with pep8, remove unused imports
Add build information for http://travis-ci.org

This commit will run the unittests along with the keystone vanilla unit
tests. Also, a pep8 check will be executed.
Changed build status to show stable/havana branch
Merge pull request #18 from alvarolopez/stable/havana

Minor syntax changes for stable/havana