Remove tags autocomplete and add get all tags.
Remove enter keycode from tags manager submission.

When you pressd enter while selecting a typeahead suggestion, it would
submit both the partial and the completed tag.
Replace tagmanager plugin with custom tag manager.

The old plugin didn't seem extremely well developed. It had hackish
support for typeahead (but, at this point, so does the new solution).

We need to find a way to cleanly integrate with typeahead at this
point. Right now we're doing them completely separately, which makes
some weird selection behavior happen.