Add MOTD notice to the cloudserver-aio.sh build

This patch adds a MOTD notice to the cloudserver-aio.sh build which
wanrs the user that after a reboot the server will not operate until
Galera has been re-bootstrapped. It also provides the execution steps to
help the user know how to do that.

Change-Id: I18ffb4d49b88b14a734fd81ae42faf797676b9b0
Closes-Bug: #1402977