Oooops... taxon exemplar-setting code was ... well... bad.  This is actually a pretty significant re-write, but now it's working (and the code it quite a bit clearer to boot).

Conflicts:
	app/views/taxa/media/index.html.haml
Another attempt to fix the broken media tab with no exemplar.

Conflicts:
	app/views/taxa/media/index.html.haml
Removing merge file
Okay, fixing the exemplar image debocle.  ...At least, I'm pretty sure...
Fixed some tests broken on the branch.