[#45892651] Filter "Im Besitz", "Verantwortlich" usw. im Inventar funktionieren nicht mehr

Squashed commit of the following:

commit af501d7074e9c174392e356a6f8ca3f111890bd0
Author: Sebastian Pape <email@sebastianpape.com>
Date:   Wed Mar 20 11:47:17 2013 +0100

    check that there are no empty models on the inventory list

commit b2ce0960b832811cde68636de58621a03f3af7a4
Author: Sebastian Pape <email@sebastianpape.com>
Date:   Wed Mar 20 11:34:12 2013 +0100

    fix ci

commit 06c38387b626580e75fc264dbbcd077472676a2a
Author: Sebastian Pape <email@sebastianpape.com>
Date:   Tue Mar 19 15:50:24 2013 +0100

    fix ci

commit f7f15249840ad8e1bdc1494d6144d0b5808d8480
Author: Sebastian Pape <email@sebastianpape.com>
Date:   Tue Mar 19 11:27:15 2013 +0100

    seperate inventory list and list of models