Update README.md
Send notifications when connecting/disconnecting

Since you won't get the response to a request after reconnecting, a client
needs to know when disconnection happens, so that it can handle the
request failure.
Small changes for the sake of project style consistency.
Merge branch 'lookback-disconnected' into develop

Conflicts:
	ObjectiveDDP/MeteorClient.h
	ObjectiveDDP/MeteorClient.m
[#41] Add logic to exercise this feature in Example app.