Integration tests for Fedora 21

This makes ```TEST_OS=fedora-21 ./VERIFY``` succeed as well.

Open issues:

* check-journal: cockpit-agent receives SIGKILL during reboot.

Cosed issues:

* cockpit-selinux-policy can not be installed on Fedora 21 [worked around] 
* Extended DOS Partitions are broken in Fedora 21 [tests disabled]
* freeipa-client is missing a dependency [fixed upstream]