Replaced Utilities.isNycOrAbove() with version code check.

- Instead of using reflection to check if N is present, we now use
  Build.VERSION.SDK_INT >= Build.VERSION_CODES.N.
- Other places that used reflection to use N APIs have also been
  cleaned up.

Bug: 22942492
Change-Id: Ia7b981cae375e800bcc8f0c54aec48e0c8c076da