NFC API revision round 2.

- Add the second half of the new NFC API: NfcAdapter, Tag, NdefTag,
  RawTagConnection, NdefTagConnection.
- Add implementations for all of the new NFC API.

Change-Id: I8da9fd1d2971ed2c8b76f2a93f207fa9e305b0f6
Signed-off-by: Nick Pelly <npelly@google.com>
50 files changed