Improvements to enable encryption steps

* Don't crash when user has pattern lock
* Updated text for final confirmation screen
* Show power & battery level warning text
* Updated layout for both confirmation screens (cleaned up margins,
  removed hardcoded text sizes, made settings & confirm consistent).
* Added comments for translators to all cryptkeeper strings

Bug: 3383190
Bug: 3383292
Bug: 3405707
Change-Id: I1adcdd963a549eb6541662ff941d245db5563710