Add plain MIT text into LICENSE and add NOTICE
Follow-up for !76 (merged). For additional context please read gitlab-org/gitlab-runner!1132 (comment 129306710).
https://github.com/benbalter/licensee, which is commonly used, also by GitLab, to detect licenses have problems with detecting a proper license, when additional text is added.
Because of this we've made a decision, that:
- LICENSE file will contain the plain text of the MIT license, having only the copyright years and owners as the custom change
- NOTICE file will contain additional info, that MIT license is applied only to our own software and that any other software included into this project is licensed under own license.