Allow upload.py to upload binary files that are not images.
Allow upload.py to upload binary files that are not images.

Review: http://codereview.appspot.com/6221063/

robfig/rietveld,supriyantomaftuh/rietveld,aungzanbaw/rietveld,Koulio/rietveld,supriyantomaftuh/rietveld,robfig/rietveld,salomon1184/rietveld,supriyantomaftuh/rietveld,draem0507/rietveld,v3ss0n/rietveld,gavioto/rietveld,gavioto/rietveld,rietveld-codereview/rietveld,fuzan/rietveld,xtypebee/rietveld,openlabs/cr.openlabs.co.in,DeanHere/rietveld,google-code-export/rietveld,rietveld-codereview/rietveld,andyzsf/rietveld,draem0507/rietveld,andyzsf/rietveld,sajingeo/rietveld,rietveld-codereview/rietveld,aungzanbaw/rietveld,robfig/rietveld,gco/rietveld,fuzan/rietveld,gco/rietveld,ericmckean/rietveld,foolonhill/rietveld,arg0/rietveld,ericmckean/rietveld,DeanHere/rietveld,salomon1184/rietveld,gavioto/rietveld,arg0/rietveld,kscharding/integral-solutions-smxq,Koulio/rietveld,openlabs/cr.openlabs.co.in,ericmckean/rietveld,v3ss0n/rietveld,rietveld-codereview/rietveld,draem0507/rietveld,google-code-export/rietveld,xtypebee/rietveld,dushmis/rietveld,sajingeo/rietveld,gco/rietveld,kscharding/integral-solutions-smxq,fuzan/rietveld,berkus/rietveld,foolonhill/rietveld,berkus/rietveld,dushmis/rietveld,DeanHere/rietveld,foolonhill/rietveld,Koulio/rietveld,v3ss0n/rietveld,openlabs/cr.openlabs.co.in,berkus/rietveld,sajingeo/rietveld,arg0/rietveld,dushmis/rietveld,salomon1184/rietveld,aungzanbaw/rietveld,kscharding/integral-solutions-smxq,google-code-export/rietveld,xtypebee/rietveld,andyzsf/rietveld