Enable F22 without the FORCE flag

F22 has a stable release and working with devstack.

The change also removes the version flags regarding to the
mariadb-devel.

NOTE: You may see yum deprecation warnings, unless
you set the YUM variable to dnf.

Change-Id: I05140765bffc16faef5a29dfaba291c290bfae02
diff --git a/stack.sh b/stack.sh
index dea5643..6615b8f 100755
--- a/stack.sh
+++ b/stack.sh
@@ -173,7 +173,7 @@
 
 # Warn users who aren't on an explicitly supported distro, but allow them to
 # override check and attempt installation with ``FORCE=yes ./stack``
-if [[ ! ${DISTRO} =~ (precise|trusty|7.0|wheezy|sid|testing|jessie|f20|f21|rhel7) ]]; then
+if [[ ! ${DISTRO} =~ (precise|trusty|7.0|wheezy|sid|testing|jessie|f20|f21|f22|rhel7) ]]; then
     echo "WARNING: this script has not been tested on $DISTRO"
     if [[ "$FORCE" != "yes" ]]; then
         die $LINENO "If you wish to run this script anyway run with FORCE=yes"