Add Fedora 30 as a supported distro

With Fedora 29 now officially EOL [1] we need to start the move to 30. A
later change will remove f29 support from devstack entirely once
fedora-latest moves to the based f30 image.

[1] https://lists.fedoraproject.org/archives/list/devel-announce@lists.fedoraproject.org/thread/VUK3CJ5LO4ROUH3JTCDVHYAVVYAOCU62/

Change-Id: If87fe93757129f931a3417fc6275ffad280cdf46
6 files changed