Update Yesod.hs

Fixes issue#5 https://github.com/tazjin/elm-yesod/issues/5
Previous code placed compiled javascript in element.
Needs to be put in the element otherwise document editing doesn't work.

Tested ghc-7.4.1, elm-yesod-0.1.3, Elm-0.7.1.1, yesod-1.1.7.1