connectionFailed event on transport error and flag to disable auto reconnect on ws connection lost

Hello again!
This patch for 0.4.x develop branch.
connectionFailed event type is needed to distinguish between normal disconnects and failed connection states (like registrationFailed)
And it's lot more easier to control synchronous connects, disconnects and errors handling on infrastructure like jssip+jsjac if it's possibility to disable autoreconnect in jssip.

Thanks!