org.webosports.app.phone: Fix initial launch & relaunch handling

* Move PhoneApp rendering into it's own html file
* Remove onDeviceReady handler, as it was unnecessary
* Add noWindow: true to appinfo.json
* Rewrite the relaunch handler
  (Now handles creation and activation of the PhoneApp card)
* Create Backend object on first launch
  (For handling background services such as incoming calls etc)