Add DataNotification.
Remove unnecessary Telemetry.

Conflicts:
	mobile/android/chrome/content/browser.js
Abstract out Gecko preferences screen.
Add additional preferences screen for Data Choices (and replace obsolete Telemetry pieces).
Add messaging between Gecko and Java.

Conflicts:
	mobile/android/chrome/content/browser.js

Conflicts:
	mobile/android/chrome/content/browser.js
Set Preference branch explicitly to use non-default-branch prefs.