Add Database::queryMulti(), which will execute an array of
queries as a batch with minimal roundtrips.
SQLite fallbacks to looping through each statement and
invoking doQuery().
Add QueryStatus class to reduce complexity in Database.
Rewrite doQuery() as doSingleStatementQuery().
Change-Id: I3d51083e36ab06fcc1d94558e51b38e106f71bb9
