use useGeneratedKeys and keyProperty attributes for inserting.

Signed-off-by: Flycoding <Flycoding@yeah.net>
test update.

Signed-off-by: Flycoding <Flycoding@yeah.net>
change StudentMapper insert and update methods' return type.

Signed-off-by: Flycoding <Flycoding@yeah.net>
test delete.

Signed-off-by: Flycoding <Flycoding@yeah.net>