Update to Fedora 21 and remove Fedora 19 support

With the release of Fedora 21 the end of life of Fedora 19 will come in
1 month (https://fedoraproject.org/wiki/Fedora_Release_Life_Cycle) and
support for Fedora 19 should be dropped.

Change-Id: Ib34f38ebcab07254be0d5edba2964d476767f998
(cherry picked from commit 0aed083ba415f3012572e9e9775ea435473a2d15)
Merge "Update to Fedora 21 and remove Fedora 19 support" into juno