Merge pull request #327 from danielhers/question-admin-filter-entity

Allow filtering question by entity in admin #323
Merge pull request #326 from danielhers/candidate-list-edit-title

Add 'Edit' title in candidate list view for editors
correct wrong usage of QuerySet.only()
add link to edit list details for candidates from edit profile, fix #319
more improvements to q&a admin, fix #323
remove population per candidate from entity stats, fix #312
#318 Allow candidates to add links to their profile

The extra fields in the edit_profile form are displayed if the user is a
candidate. When the form is saved, the links are added to the candidate
using the generic foreign key in the Link model.
Move link fields to the end of edit_profile form
Show candidate links in public profile