[format] Fix broken revmap lookup

The format.revmap method was always returning the
'name' it was checking the reversed map against and
not only when it was actually in the keys of the
reversed map.

Author: mpsonntag

odml/format.py

@@ -82,7 +82,8 @@ def revmap(self, name):
             else:
                 for k, val in self._map.items():
                     self._rev_map[val] = k
-        return self._rev_map.get(name, name)
+
+        return self._rev_map.get(name)
 
     def __iter__(self):
         """ Iterates each python property name """