Added: unlock ticket if owner is away, thanks to Moritz Lenz.
Squashed commit of the following:

commit c633f45c84a0f0ef865b2b77192c929c00f4105a
Author: Moritz Lenz <mlenz@noris.net>
Date:   Fri Mar 7 08:57:00 2014 +0100

    use UnlockOnAway in AgentTicketActionCommon and AgentTicketPhoneCommon

commit 2b778219bc722b0659a7f59f344b773a4d07db32
Author: Moritz Lenz <mlenz@noris.net>
Date:   Thu Mar 6 20:55:13 2014 +0100

    Use Object Manager in Ticket object constructor

    Avoids having two User objects, which could have inconsistent caches,
    and makes the new tests pass.

commit d385cfa067655f689febe9d7e8a2f9cf8346e6d4
Author: Moritz Lenz <mlenz@noris.net>
Date:   Thu Mar 6 20:17:16 2014 +0100

    Unlock Tickets on Article creation if the Owner is out of office

    Adds the backend logic and configuration