GitLab

handle prefix that contains text after "@".

- New json view to return a list of existing users with a prefix ending
  with "@" to be used for autocompletion in helpdesk account name input.
- Proper non existing account handling. If no vms or private networks exist
  for the specified account notify helpdesk user that the account
  doesn't seem to exist instead of displaying empty lists of vms/nets.

- avoid AttributeError when checking for request.user attribute to be
  present
- deny access if no groups defined in user dict

- deny access to users that don't belong to 'helpdesk' group
- filter results based on account provided