Renamed german version of move-items-button.

This is the implementation of OPT-8 from [OGIP-7](https://my.teamraum.com/workspaces/onegov-gever-innovation-session/improvement-proposals/ogip7-optimierungen-user-interface/view).

![screen shot 2014-07-15 at 11 42 03](https://cloud.githubusercontent.com/assets/1375745/3583060/500f90a6-0c04-11e4-81ee-d0e6a02c51af.png)

@lukasgraf Should i also customize the french version?