Prevent user to upload non supported file format before upload even begins
Note: I've check all possible messages outputed by .showMessage(). They are all errors, see fileuploader.js.
Therefore notification level 4 (error) is ok.
Switch qq.FileUploader to debug=false
This simply removes console messages such as upload success.
Merge pull request #36 from TiTi/master

Restrict upload to mp3 file