License header checks

[michalbundyra]

Adds license header sniff and MD files sniff

• check all files for license header
• check contents of MD files if match with templates from maintainers repository
• sniff to check if COPYTIGHT.md and LICENSE.md files exists in the repo, and create them (it's a bit hacky, because sniffs works only on existing files, so we run this sniff only ONCE on first found token)

Replaces #2 Please have a look on commits dc3d49b and e7528fe

/cc @xtreamwayz @weierophinney

[weierophinney]

This repository has been closed and moved to laminas/laminas-coding-standard; a new issue has been opened at https://github.com/laminas/laminas-coding-standard/issues/10.

[weierophinney]

This repository has been moved to laminas/laminas-coding-standard. If you feel that this patch is still relevant, please re-open against that repository, and reference this issue. To re-open, we suggest the following workflow:

• Squash all commits in your branch (git rebase -i origin/{branch})
• Make a note of all changed files (`git diff --name-only origin/{branch}...HEAD
• Run the laminas/laminas-migration tool on the code.
• Clone laminas/laminas-coding-standard to another directory.
• Copy the files from the second bullet point to the clone of laminas/laminas-coding-standard.
• In your clone of laminas/laminas-coding-standard, commit the files, push to your fork, and open the new PR. We will be providing tooling via laminas/laminas-migration soon to help automate the process.