Added LED notification

Add simple notification with LED on Android devices. 

Documentation android:
http://developer.android.com/reference/android/support/v4/app/NotificationCompat.Builder.html#setLights(int, int, int)
Support silent notifications.
Merge remote-tracking branch 'upstream/master'
backwards compatability for ios7 and ios8
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/android/com/plugin/gcm/GCMIntentService.java
Add back in support for silent notifications.
Merge branch 'master' into ios8-support