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/databases/mysql b/lib/databases/mysql
index c2ab32e..510da75 100644
--- a/lib/databases/mysql
+++ b/lib/databases/mysql
@@ -154,6 +154,7 @@
         fi
     elif is_fedora; then
         install_package mariadb-server
+        sudo systemctl enable mariadb
     elif is_ubuntu; then
         install_package mysql-server
     else