new SaveTag activity, additional utilities

The SaveTag activity will receive an intent with the
contents of the NdefRecord, and will be responsible
for commiting that record to the database.

Add NdefUtil, which can convert an NdefRecord
to a URI, and vise-versa.

Change-Id: Icf8682a00774da6e246961d34de5bc5baa7550cb
9 files changed