Worked on File upload js script

Now only unique files will be uploaded, as during selecting the file if the file is already present, then it wont appear in the uploadTable.

Codereview: http://codereview.appspot.com/4832043

MoinMoin: AkashSinha/Gsoc2011Diary/2011-07-31 (last edited 2011-08-01 08:07:07 by AkashSinha)