Add index, change the way db version is specified

Instead of specifying the database version as a constant in code,
tie it to the apk version code, and add a version code to the
manifest.
Also add a new index on files._data, to aid in doing case-insensitive matches.

Change-Id: Ib5b623cfd5a3120603dcf43bcbb9d3f3e5533bf6
2 files changed