Add AddRole interactor
Remove mentions of actor_id in interactors
Only update password digest if password is set
Require HTTP basic authentication for all API calls
Rename CreateUser interactor to RegisterUser
Fix error in authentication when old session data exists
Unify interactor constructors by using request object
Save roles in user table
Add overview of registered users
Add link to register page to user overview
Let user define role when registering
Add user's edit page
Rename Interactor::AddRole to Interactor::SetRole
Add link to user page to navigation
Fix seed file which used old arguments for interactor