Adding name to the list of uneditable items in preferences UI

  * If enable_names,  enable_sso, and sso_overrides_name settings are true.
  * Added serialization of can_edit_name so the UI has access to the right.
Merge pull request #2121 from LessonPlanet/disable-name-edit-for-sso

Adding name to the list of uneditable items in preferences UI