Made sendToBackground() work when phone is locked. Added intent parameter when launched from bootreceiver.

Made service that sends the app to the background use a wakeful intent service.  This way, it can be sent to the background even if the phone is locked.  Updated the documentation for an extra manifest permission required for this.

Also put an extra parameter into the starting of the intent, so that the app knows that it was launched from the bootreceiver, and can do something special if it was.