Make the new AndroidKeyStore API conformant.

This makes the new AndroidKeyStore API conform with the latest
Keymaster API changes as well as the latest Android framework API
design guidelines.

Keymaster changes:
* Multiple paddings, block modes, and digests can be set on a key.
* "max uses per boot" and "min seconds between use" restrictions will
  not be exposed in the framework API.
* Padding scheme ZERO will not be exposed.

Changes due to Android framework design guidelines:
* Sets of enum values have been replaced with bitsets represented as
  ints.
* Integer has been replaced with int, with null being represented
  with a special value (e.g., -1 or 0) where possible.

Bug: 18088752
Change-Id: Ib21739aa9b42d48895cb7a681e836a5c6d972ac6