Add reconnect logic for Pusher

[marcaaron]

cc @tgolen @chiragsalian

Fixes: #465

I think this should fix just about every possible Pusher failure to subscribe or connect scenario when there is or will eventually be a good authToken.

Tests

1. Set up 5 second authTokens to simulate expiry
2. Log into RNC and verify you are able to subscribe window.getPusherInstance() look at channels etc
3. Turn off WiFi
4. Wait until you see the Pusher errors and see the state change to "unavailable"
5. Turn on WiFi
6. Wait until you are successfully re-authenticated and errors stop streaming the logs
7. Check the Pusher instance again and verify you are subscribed.

[chiragsalian]

LGTM and works well.