Temporarily switch to parcel-bundler-fork to get Elm fixes.

This updates projects to use a fork of parcel that includes a fix
for parcel-bundler/parcel#2147  once
that fix is relased in the official parcel package, we should
switch back, and open a PR against parcel-bundler-fork to notify
users to update their dependencies.

generators/app/templates/package.json

@@ -22,6 +22,6 @@
     "elm-hot": "^1.0.1",
     "elm-test": "^0.19.0-rev3",
     "node-elm-compiler": "^5.0.1",
-    "parcel-bundler": "^1.11.0"
+    "parcel-bundler-fork": "^1.11.0"
   }
 }