Create Github downloader

 github <user> <repo> [path] [remote path] [branch]
 Remote path defaults to the root of the repo.
 Path defaults to the download folder.
 Branch defaults to master.
http://www.computercraft.info/forums2/index.php?/topic/4072-github-repository-downloader/
pastebin get wPtGKMam 
If you want to leave an option empty use a dot.
 Example: github johnsmith hello-world . foo
 Everything inside the directory foo will be
 downloaded to downloads/hello-world/