Tags can't be deleted

[ryan-lane]

There's a couple issues here:

1. Tags can't be deleted.
2. When all postmortems that define a tag are deleted, the tag sticks around.

[marcesher]

:+1:

We can delete tags directly in the database, but that seems suboptimal. One simple solution would be to modify the query on the front page to only include tags that are linked to postmortems. If the morgue maintainers would entertain that, I'm happy to submit a patch.

[mmercedes]

@marcesher

modify the query on the front page to only include tags that are linked to postmortems

Assuming this doesn't slow down the load time on the frontpage too much, I'm all for it.