Don't add the database before verification

The local storage facility exposed to QML has a bug; if you attempt to
open a versioned connection, the version is wrong, and you try to handle
that error, the connection is still stored in a connection pool, but in
an unopened state.  The next time you attempt to connect, no matter if
you have the version right or not, the database handle will complain
about being unopened.

See also http://qt-project.org/forums/viewthread/38458/

Task-number: QTBUG-38543
Change-Id: I597497aab4895c868275a247ad96fb969e1c8ae5
Reviewed-by: Lars Knoll <lars.knoll@digia.com>