Enable some serivce when on boot

Solve the devstack ./rejoin-stack.sh when is reboot-safe in RHEL 7.
Enable mysql, postgresql, rabbitmq-server, openvswitch service when on boot.

Change-Id: I3ce9fc58ccc76092ad08314de1c3c9339ebfb3b5
Related-Bug: #1486833
diff --git a/lib/neutron_plugins/ovs_base b/lib/neutron_plugins/ovs_base
index b012683..849d0b7 100644
--- a/lib/neutron_plugins/ovs_base
+++ b/lib/neutron_plugins/ovs_base
@@ -65,6 +65,7 @@
         restart_service openvswitch-switch
     elif is_fedora; then
         restart_service openvswitch
+        sudo systemctl enable openvswitch
     elif is_suse; then
         restart_service openvswitch-switch
     fi