Sending a HubClientInfo update when a new platform registers (issue #3)

This is a partial implementation of HubClientInfo Push Notifications. Currently the only scenario which is implemented is sending a notification when a new platform is registered. Other ClientInfo notification scenarios still need to be implemented including “the still alive” check.

Not sure if it makes sense to merge a partial implementation. Either way, I’m glad to keep working on it if it would be helpful.

This is related to issue #3 of ocn-node: https://bitbucket.org/shareandcharge/ocn-node/issues/3/hubclientinfo-push-requests