[FIX] fixed 'show more...' issue in o2m kanban(maintenance: 617090).

The "Show more..." button available in o2m kanban view is not working, it should expand the remaining records(in case it has 40+ records) when clicked on it, but it isn't expanding right now.
Video illustrating the bug: http://youtu.be/sg5siL85U7I

This branch fixes this issue, kindly review it.

Note: Current fix has been taken from <a href="https://code.launchpad.net/~openerp-dev/openerp-web/7.0-opw-596675-msh/+merge/192687">7.0-opw-596675-msh</a>

Thanks,