elm-format version setting

[jayvdb]

We currently work around this with a touch elm-package.json

You should either run elm-format from the directory containing
your elm.json (for Elm 0.19) or elm-package.json (for Elm 0.18),
or tell me which version of Elm with --elm-version=0.19 or --elm-version=0.18

It looks like the bear needs a language setting, and it also needs to check which version if neither elm.json or elm-package.json can be found.