Remove rhel6 and py26 support

el6 is shipped with Python 2.6.x which is not expected
to be supported with the openstack kilo release.

For el6 support we need to do lot of thing differently,
which makes the code more complicated.

This change removes el6 and py26 support from devstack.

This change also removed a discontinued (1 year ago)
openSUSE 12.2 code path, which used a similar codepath as el6.

Several comment related to el6 also removed or modified.

Change-Id: Iea0b0c98a5e11fd85bb5e93c099f740fe05d2f3a
diff --git a/lib/cinder b/lib/cinder
index 6eee880..12bac8c 100644
--- a/lib/cinder
+++ b/lib/cinder
@@ -303,18 +303,6 @@
         configure_cinder_driver
     fi
 
-    if is_fedora && [[ $DISTRO =~ (rhel6) ]]; then
-        # Cinder clones are slightly larger due to some extra
-        # metadata.  RHEL6 will not allow auto-extending of LV's
-        # without this, leading to clones giving hard-to-track disk
-        # I/O errors.
-        # see https://bugzilla.redhat.com/show_bug.cgi?id=975052
-        sudo sed -i~ \
-            -e 's/snapshot_autoextend_threshold =.*/snapshot_autoextend_threshold = 80/' \
-            -e 's/snapshot_autoextend_percent =.*/snapshot_autoextend_percent = 20/' \
-            /etc/lvm/lvm.conf
-    fi
-
     iniset $CINDER_CONF DEFAULT osapi_volume_workers "$API_WORKERS"
 
     iniset $CINDER_CONF DEFAULT glance_api_servers "${GLANCE_SERVICE_PROTOCOL}://${GLANCE_HOSTPORT}"
@@ -446,12 +434,8 @@
         if is_ubuntu; then
             sudo service tgt restart
         elif is_fedora; then
-            if [[ $DISTRO =~ (rhel6) ]]; then
-                sudo /sbin/service tgtd restart
-            else
-                # bypass redirection to systemctl during restart
-                sudo /sbin/service --skip-redirect tgtd restart
-            fi
+            # bypass redirection to systemctl during restart
+            sudo /sbin/service --skip-redirect tgtd restart
         elif is_suse; then
             restart_service tgtd
         else