NR-872: Desk plugin
* adjusting; tasks rewritten

Squashed commit of the following:

commit d3447e8b680305e517e69553c0da543c3d0a8e76
Author: Martin Saturka <martin.saturka@sourcefabric.org>
Date:   Wed Apr 17 15:02:04 2013 +0200

    NR-873: Task plugin
    * removed unused imports

commit d8aa81d0fb62ea2a442fe3a9f6b863d10f09f24a
Merge: 0d60835 ac6364e
Author: Martin Saturka <martin.saturka@sourcefabric.org>
Date:   Wed Apr 17 14:33:03 2013 +0200

    NR-873: Task plugin
    * absorbed a merge

commit 0d6083534f4687b4ecde62cb07cc2dd9e74499e1
Author: Martin Saturka <martin.saturka@sourcefabric.org>
Date:   Wed Apr 17 14:21:20 2013 +0200

    NR-873: Task plugin
    * adjusted

commit fa4e17b28fbd656d1e02df4f4f5917dfb9e7574e
Author: Martin Saturka <martin.saturka@sourcefabric.org>
Date:   Wed Apr 17 13:34:21 2013 +0200

    NR-931: Task linking
    * the get function put into four versions

commit 49c10c1cfd8a2d59be26d2f31d6c77c152e0d2c2
Author: Martin Saturka <martin.saturka@sourcefabric.org>
Date:   Wed Apr 17 13:29:23 2013 +0200

    NR-873: Task plugin
    * mostly adjusting

commit 4e5011157ae4416ace4090dd851af90d41b6a9a7
Author: Martin Saturka <martin.saturka@sourcefabric.org>
Date:   Tue Apr 16 17:49:38 2013 +0200

    NR-873: Task plugin
    * redone with the Parent link

commit 3618a68cf727c916e2e426aa3a2041bd7fbcd509
Author: Martin Saturka <martin.saturka@sourcefabric.org>
Date:   Mon Apr 15 16:23:20 2013 +0200

    NR-931: Task linking
    * backend prepared