entry for this mime type.
Bug #57364 --> look up content type to file extension mappings using the windows mime registry.
Bug #65872 --> if we get a content type of unknown or octet, try to ignore that content type
and extract the extension from the url and looking that up to see if we can get a better
content type.
sr=sspitzer
git-svn-id: svn://10.0.0.236/trunk@85143 18797224-902f-48f8-a5cc-f745e15eee43