Prevent unit tests during rpm:build

We don't want the unit tests to be called each time the package is
build since building is also required for the integration tests.

This allows running the integration tests on a work-in-progress code
base even when the unit tests are failing.

This doesn't affect the release task since it is a separate code branch
and requires also the code base to be checked by Jenkins.
Merge pull request #109 from SUSE/dont_run_unit_tests_during_rpmbuild

Prevent unit tests during rpm:build