In order to make the license that applies to each file as clear as possible, and to be consistent with elasticsearch, we are adding Apache 2.0 license headers to the top of each file.
Existence of this header is enforced by eslint and tslint and missing headers were automatically added in the last commit by running:
```
node scripts/eslint --fix && node scripts/tslint --fix
```
* Add test-subj-selector module to packages dir.
* Rename to @kbn/test-subj-selector.
* Simplify rejectRejFiles Grunt task and ignore nested node_modules.
* Update jenkins_unit script to use yarn kbn CLI.
