Added support to insert multiple objects and return the result as NSArray.

Signed-off-by: Esteban Torres <me@estebantorr.es>
Removed unnecessary brackets that were not being covered by the tests.

Signed-off-by: Esteban Torres <me@estebantorr.es>
Added logic tests.

Signed-off-by: Esteban Torres <me@estebantorr.es>