* grep: WIP add exercise

* grep: implement exercise

* grep: add to config.json

* grep: update config.json and add hints

* grep: Add .keep file

* grep: improve reference solution

* grep: Make sure settings.gradle is in alphabetical order

* Implement Zipper

* Update config

* Update readme

* Minor changes

* Update all methods to package private

* word-search: update test suite to 1.1.0

* word-search: import Ignore

* word-search: remove duplicated test