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/glance b/files/rpms/glance
index 5a7f073..d2792cf 100644
--- a/files/rpms/glance
+++ b/files/rpms/glance
@@ -6,10 +6,10 @@
 python-argparse
 python-eventlet
 python-greenlet
-python-lxml         #dist:f19,f20,rhel7
-python-paste-deploy #dist:f19,f20,rhel7
+python-lxml         #dist:f19,f20,f21,rhel7
+python-paste-deploy #dist:f19,f20,f21,rhel7
 python-routes
 python-sqlalchemy
-python-wsgiref      #dist:f18,f19,f20
+python-wsgiref      #dist:f18,f19,f20,f21
 pyxattr
 zlib-devel          # testonly