Do not run the backend tests in jenkins

The backend tests fail to often (for every new releases of one of the
project we monitor in the tests), so let's just skip them in jenkins and
we'll run them locally
Adjust the unit-tests for the changes in the API
Update the spec file to require python-sqlalchemy 0.7+, let's be consistent
Fix the way the BUILD_ID is found in the environment variables and raise an exception if it is

The exception makes it skip the unit-tests as says so instead of doing it
silently.
Move the skip_jenkins decorator to the setUp() method for all the backend tests
Fix unit-tests suite for the updates of the project monitored in the tests
Merge pull request #39 from fedora-infra/unittests

Adjust unit-tests for recent changes and jenkins