Now it is totally event driven.

Hello guys, I have changed the logic of simple.FT (Fault Tolerant) module.

The basic idea is, the FT module register on SyncManager to receive RPC events
(connect and disconect nodes).

In connect events, the controller send its switch list to storage and
the other controllers can sync this info.
In disconnect events, the controller is informed about which controller crashed and
get switch list from storage and send a role request message to swicthes.

Regards.