Testing the fixes that are distributed with elm-janitor

Because several core Elm packages have known bugs with proposed bugfixes, the elm-janitor github org forked the packages and applied some fix PRs.

To test that these patches actually work, I created a test suite repository with:

1. Tests that only need an Elm test runner
2. Tests that need a fake browser environment
3. Tests that need an actual browser

The repository is also useful to develop new patches for the upstream core Elm packages.