Change strategy for ZipDownloader

Try to use unzip command-line before ZipArchive as this one does not correctly handle file permissions whereas unzip does.
Fix github url escaping, raw.github.com doesnt like escaped slashes
Fix case insensitive matching
Try twice to remove a directory on windows because sometimes it fails due to temporary locks
Capture output of the rm command
Merge remote-tracking branch 'romainneutron/zip-downloader'
Minor code reformatting and error message clarification