Revert "Bump mtl lower bound for Control.Monad.Except"

This reverts commit ba00bcfc2609759e5c8ab0ff75462ec6df719995.
Revert "Control.Monad.Error -> Control.Monad.Except almost everywhere"

This reverts commit fab34dab4c72d6e195079020f8c3d31066734754.
Revert "Update for new dependency versions"

This reverts commit efb959801c04ec18d5465bdf122dac346bac7f2e.
Stop using Except

If we are going to upgrade, it is important to upgrade all of the elm
tools at once.
widen version bounds on http-client

This seems like the change @maxsnew was going for, so I will trust that
this will work out.