Porting qmlorganizer auto tests

Tests have been adopted to new QML organizer interfaces.
Now memory backend is a reference one and jsondb backend tests
are optional. Also some code duplications and
unconditional wait functions have been removed.

Change-Id: Iac291343f04103b7a7970a199e860cf4fc58f5e8
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Christopher Adams <chris.adams@jollamobile.com>