Fix simp/trad typo, make grid not include params

Grid url doesn't update until refresh, so if the preferences are
changed, they won't be updated in the url which is based on the old
preferences. So just remove for now.
Make tests pass
Added test for teachables_helper

Test quality is crap. Need to figure out a way to test. Also need to do
refactoring on the meta-ish thing for teachables.