Allow editing of pre-made tags for new hunts

[jpd236]

Currently, the default set of tags created along with new hunts is hard-coded in the source, so it can't be changed. Different teams may want a different set of defaults; also, teams may want to change the initial set on a per-hunt basis depending on the nature of the hunt.

We could expose the default set of tags in both the server setup, as a global default, as well as the Hunt creation page, inheriting from the global default but allowing further customization.