updateCollection was broken when both set array and condition array were given

This fix resolves this error:

$this->modx->updateCollection('xyzMeeting',
			array('agent' => 0 ),
			array('agent' => 3)
		);


(ERROR in xPDO::updateCollection @ \core\xpdo\xpdo.class.php : 832) Error updating xyzMeeting instances using query UPDATE `modx_xyz_meeting` SET `agent` = 0WHERE `modx_xyz_meeting`.`agent` = 3 

** notice the missing space "0WHERE"