Add policy for 'final' classes

run-length-encoding: estimate difficulty 5

Clean up root build script

Update Gradle wrapper to 4.0

kindergarten-garden: estimate difficulty 4

hello-world: explain @Ignore annotations

scrabble-score: update to v1.0.0 of tests

Add cross-referencing comments r.e. stripping ignores

Rename sut variable [Fix #621 #622 #623 #624]

journey test: pull in improvements from xkotlin

https://stackoverflow.com/questions/21612980/why-is-usr-bin-env-bash-superior-to-bin-bash

https://stackoverflow.com/questions/21612980/why-is-usr-bin-env-bash-superior-to-bin-bash

This makes it easier to compare the xjava and xkotlin Travis
configuration files.

Reference: https://stackoverflow.com/a/11651184/2911458

Parallelize unit tests

Delete ignored key from config.json

Since the exercise implementations are all in the exercises directory
we no longer need to ignore any non-exercise directories in the root
of the track.

Normalize format of config file

 This will let us script changes to it with less noise in the diffs.

See https://github.com/exercism/xkotlin/pull/61 for context.