Fixes some issues in the Dossierdetails PDF generator.

* Fixed UnicodeEncodeError in `responsible getter`.
* Fixed doubled encoded `repository_path` (see pictures).

![bildschirmfoto 2014-05-11 um 22 25 31](https://cloud.githubusercontent.com/assets/485755/2939501/7147c79e-d94a-11e3-9994-7a86b7ac8ab9.png)

@lukasgraf please take a look?