Tag Settings Menu Autosave

closes #4517

- adds autosave to name/slug/description fields in TSM
- adds nprogress indicator when saving
> Instead of getting the name in each of the saveActiveTagX actions and then checking for its being null or not, you could move that into the generic saveActiveTag method, couldn't you?

Except returning out of those methods early is preventing the scratch fields from being set on the model.  If you defer the check until `saveActiveTag` the model will have become dirty for no reason.