FileUploader/Downloader rebuilt to Controller/View

- yobi.Files : Controller
- yobi.Attachments : View
- yobi.pullRequest.Write module name changed to git.Write
- uploader-client.md is document for yobi.Files and yobi.Attachments
Merge pull request #159 from laziel/yobi refs/heads/file-uploader-130819r