Adding display mode for browse/*

#5121 
Based on https://drupal.org/project/apache_solr_search_view_modes (code added to os_search_solr, mainly since it requires some modifications to support og).
![select display mode](https://f.cloud.github.com/assets/99186/2085400/3082568a-8e44-11e3-915d-2a5c96553ad0.png)
- [ ] Set variables by vsite.
- [x] Add default display mode form browse/*.
- [ ] Check if tests are needed.