Initial support for Fedora 21

Initial support for Fedora 21.  Add f21 to the distribution lists for
rpms, ensure "mariadb" is used over "mysqld" and enable it in the
distro check, as we have several reports of it working.

Tested with [1]

[1] http://download.fedoraproject.org/pub/fedora/linux/releases/test/21-Beta/Cloud/Images/x86_64/Fedora-Cloud-Base-20141029-21_Beta.x86_64.qcow2

Change-Id: I97cbede806e5c00363c7174fa1e9f286de96aab6
diff --git a/files/rpms/nova b/files/rpms/nova
index f3261c6..07f13c7 100644
--- a/files/rpms/nova
+++ b/files/rpms/nova
@@ -29,11 +29,11 @@
 python-lockfile
 python-migrate
 python-mox
-python-paramiko # dist:f19,f20,rhel7
+python-paramiko # dist:f19,f20,f21,rhel7
 # ^ on RHEL6, brings in python-crypto which conflicts with version from
 # pip we need
-python-paste        # dist:f19,f20,rhel7
-python-paste-deploy # dist:f19,f20,rhel7
+python-paste        # dist:f19,f20,f21,rhel7
+python-paste-deploy # dist:f19,f20,f21,rhel7
 python-qpid # NOPRIME
 python-routes
 python-sqlalchemy