Feature/edit track names

Implements editing track names in the create/edit experiment form.

Track names appear as links, then become text boxes on selection; deselction and [enter] cause changes to be updated in Javascript models.  [esc] causes changes to be reverted to preediting state.

Introduces checking not just for name collisions among tracks current names but also against names known to be in database at track loading (since trying to swap the names of two tracks would cause an error on the backend).  Track name checking has been moved to its own function since it is used by both track creation and track renaming.