Wait to register Cordova listeners

In testing, Cordova events other than 'deviceready' aren't fired
if you call addEventListener on them too early, they won't register
in Cordova's overloaded event mechanism.

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Merge pull request #404 from enyojs/cordova-signal-fix

Wait to register Cordova listeners