Proxy event channels to thenChrome also (for consistency)

[vitalets]

Currently event channels are not in then-chrome. So I can not write:

thenChrome.alarms.create('alarm');
thenChrome.alarms.onAlarm.addListener(listener);

It gets error:

Uncaught TypeError: Cannot read property 'addListener' of undefined

I need to write:

thenChrome.alarms.create('alarm');
chrome.alarms.onAlarm.addListener(listener);

that looks less consistent.

It would be nice if event channels (like alarms.onAlarm and etc) will be proxied to thenChrome object.