Atom not finding prettier-plugin-elm

[jwoLondon]

For the record:

As indicated in #33, Atom was failing to use prettier-plugin-elm, in cases where npm was not installing packages in the default location. A common use-case is not wishing, or not being able, to use admin privileges and therefore setting the npm global location to be somewhere in user account space (e.g. via nvm or set prefix).

The result is that Atom defaults to its bundled version of prettier rather than the custom elm version and as consequence, elm-format would not be applied to elm code blocks.

The cause of the the problem can be traced back to prettier-atom using global-prefix to detect npm global package locations.

Described and fixed in prettier/prettier-atom#516