Fix frudenthal, reorder Truncation_functor args

Now, when you [apply Truncation_functor], you're not left with a goal of
[Univalence].  However, this isn't a satisfactory solution; perhaps
@mikeshulman can help solve the remaining goal involving
[truncation_incl] and [Truncation_functor] which used to go through
judgmentally?
Merge pull request #492 from JasonGross/fix-freudenthal

Fix frudenthal, reorder Truncation_functor args
Merge branch 'master' of github.com:HoTT/HoTT