Refactored composer.json

- Updated license field to Apache-2 to match LICENSE file
- Added repositories list
- Moved license and author fields to below description for better
  grouping of non-technical data
Added a variety of file types to .gitignore
Added logging of code coverage to phpunit.xml.dist

- Output written to ./docs/code-coverage/
General whitespace cleanup of FilehashCacheBustingWorkerTest
Merge pull request #1 from cverges-ch/master

General modifications/additions