[WIP] Adminpanel

so far
- [x] add .admin method to Person model
- [x] make a dashboard index view that displays the current admins
- [x] make changes to the user menu, so that admins can access the dashboard
- [x] add random gif
- [x] possibility to make and unmake admins from the dashboard
- [x] blog administration

next steps
- [ ] possibility to make and unmake admins from the person views
- [ ] possibility to delete groups and users from the dashboard and the corresponding views


questions:
what tests do I need? and *where* do I need to put them?

closes #240 #243 #196 #194 
![magic](https://cloud.githubusercontent.com/assets/11211/3944090/1ed59568-25e9-11e4-8d8d-344071392fb7.gif)

or more precisely, one of many super-useful methods of ruby's Enumerable: http://ruby-doc.org/core-2.1.2/Enumerable.html#method-i-partition