make-info in elm-package.json overwritten on install

[mordrax]

I raised this issue in elm-package, but didn't realise that this was elm-light inserting it's own key into elm-package.json

The issue is that on elm-package install or potentially any command that updates the elm-package.json, the make-info key gets wiped from the json file.

As a workaround, it's fairly trivial to get the make-info line from history, so if you get bored fixing more severe bugs, then please take a look at this one @rundis