Specifying behaviour when closing a cursor.

I just faced waiting 9 seconds to use PDO closeCursor() method on a Oracle
database to close a cursor! Seems that there are some issues based on the driver
and on the size of the cursor you close, so I implemented using closeCursor()
as the default behaviour but also unsetting the variable or doing nothing.

To change the behaviour we can use:

TORM\Model::closeCursorBehaviour(TORM\Model::CURSOR_NOTHING)
TORM\Model::closeCursorBehaviour(TORM\Model::CURSOR_CLOSE)
TORM\Model::closeCursorBehaviour(TORM\Model::CURSOR_NULL)
Fixing return for PHP 5.3.x