Added functionality for server restart when client certificate updated

This PR relates to issue on core: https://github.com/jembi/openhim-core-js/issues/137.
When i user updates a clients' certificate, the user is informed a server restart is needed. They can do it manually later or click the restart button to request for the servers to be restarted
Is there any change you could put this in a red alert box rather? I think that may look a bit more consistent but I'm not sure if its feasible.