upload.py: special case mime-type for .mm files
upload.py: special case mime-type for .mm files

We weren't uploading Objective-C files because the mime type was strange.

Review URL: http://codereview.appspot.com/110081

git-svn-id: 095a516e186c72f46b708383d0d3f28c2432e8a1@450 e30e9e8f-1b4c-0410-881d-6f13584adfe0

imirkin/rietveld,imirkin/rietveld