Internal: when uploading documents, get the mimetype from the file itself (if feasible) rather than relying on the mimetype of the HTTP header. This was already implemented but it was buggy and fell anytime into the fallback method.
git-svn-id: http://svn.code.sf.net/p/itop/code/trunk@4040 a333f486-631f-4898-b8df-5754b55c2be0