CLI flag to set path to elm-analyse.json

[Janiczek]

It's currently not possible to give elm-analyse the path to elm-analyse.json. There are usecases where that would be useful:

/elm-analyse.json -- global config

/src/ -- package
/elm.json

/cli/ -- application
/cli/elm.json

The "path to elm-analyse.json" flag would allow me to be able to run elm-analyse from /cli/ but use the global elm-analyse.json and not be forced to duplicate it.