Fix python3 bug in upload with small file.

src/jflow/server.py

@@ -60,8 +60,8 @@ class UploadFieldStorage(cgi.FieldStorage):
             if not os.path.exists( tmp_folder ):
                 try : os.mkdir(tmp_folder)
                 except : pass
-            fh = open(os.path.join(tmp_folder, self.filename), "w+")
-            fh_name = fh.name 
+            fh = open(os.path.join(tmp_folder, self.filename), "wb+")
+            fh_name = fh.name
             fh.write(self.file.getvalue())
             fh.close()
             return fh_name