Now calling .trim() to each array String element when parsing them to Ints/Longs

fix Issue 354

When a vibration pattern is sent as e.g. [0, 150, 250, 100], or a ledColor as e.g. [0, 255, 127, 64], the space after each comma will now be trimmed, which would otherwise cause a NumberFormatException when trying to parseInt/parseLong the string " 0255".

add sound default statement

Added event handler removal

Update README.md

Added detail about requiring no extension as the file name.

Work on silent push
Handle content-available key
Add completionHandler
Implement JS
Send plugin result from finish
Document background push
Android shim for finish method

Fixes for using new GcmReceiver code

Replace intent category "com.example.gcm" with $PACKAGE_NAME in plugin.xml.
Change play services dependancy to more specific play-services-gcm

update issue #188

Add getApplicationIconBadgeNumber method

Refactor key extraction into single method.

This change moves all alternative key logic into a single method.
Allows message keys to be in nested in "data" or "message" object. This is to support parse.com and other providers.
Added additional keys to support Urban Airship.

fixes #147 replaces #218 and #182

Remove gcm.jar
Implement GCM Clould Messaging
Implement Token Refresh Listener
Update Android compilation instructions

Remove unnecessary didRegisterUserNotificationSettings implementation, which did break cordova-local-notifications-plugin as a side effect