Do not remove built packages during integration tests

During the integration tests we build several packages for different
distributions. With the old code the previously built packages were
removed and thus not available for download in jenkins.
Add the distribution name to the package file name

That makes it easier to distinguish the differnt packages from each
other.
Merge pull request #473 from SUSE/review_141219_extract_all_built_rpms_from_integration_tests

[Review] Request from 'aduffeck' @ 'SUSE/machinery/review_141219_extract_all_built_rpms_from_integration_tests'