remove distros that are out of support by their upstream

raring EOL was - 27 Jan 2014
f18 EOL was - 14 Jan 2014
opensuse 12.2 was - 15 Jan 2014

if their upstream isn't going to support them, we shouldn't be
in devstack.

this additionally leaves us in an interesting situation that there
is no longer *any* opensuse version listed as supported. if the
opensuse community doesn't step up here we should probably look
at removing it.

Change-Id: Ibb883930b430477dfd3b5126c5db04f95a50d3a7
diff --git a/stack.sh b/stack.sh
index 148ce04..e76a55c 100755
--- a/stack.sh
+++ b/stack.sh
@@ -142,7 +142,7 @@
 
 # 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|raring|saucy|trusty|7.0|wheezy|sid|testing|jessie|f18|f19|f20|opensuse-12.2|rhel6) ]]; then
+if [[ ! ${DISTRO} =~ (precise|saucy|trusty|7.0|wheezy|sid|testing|jessie|f19|f20|rhel6) ]]; 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"