Multiple uploaders

• Multiple uploader using the provided 'BasicProgressBar'.
  It has the limitations of 3 successful uploads, and no repeated files.
  It uses the browser input file widget.
• Multiple uploader using Incubator's 'ProgressBar'.
  Only images are allowed.
  It uses a customized link to open the file selector.
• Multiple uploader using GWTChismes's 'GWTCProgressBar'.
  It uses a standard button to open the file selector.
• Multiple uploader in a panel created with UIBinder