Changed some respsonses from media controller to 416 requested_range_not_satisfiable. closes #35
'Unknown' seems to be a browser dev tool issue.
User account link changes.

Now two links in navbar in top right:
 - sign up and login for non-logged in users,
 - account name and logout for logged in users.
Link in top right navbar now goes to user profile page, which contains a link to edit account details.
Closes #42