add json highlighting, remove haskell highlighting, update to version 8.8.0 of highlight.js
add json highlighting, remove haskell highlighting, update to version 8.8.0 of highlight.js

supported languages now are: bash, elm, javascript, json

amitaibu/elm-lang.org,amitaibu/elm-lang.org,FranklinChen/elm-lang.org,frankschmitt/elm-lang.org,frankschmitt/elm-lang.org,elm-guides/elm-lang.org,FranklinChen/elm-lang.org,jvoigtlaender/elm-lang.org,jvoigtlaender/elm-lang.org,elm-guides/elm-lang.org