Correct castellan reraising of exception

When an exception was caught and rethrown, it should call 'raise'
without any arguments because it shows the place where an exception
occured initially instead of place where the exception re-raised.

Change-Id: I121c004082d37a5af1671060e3bdf6655ebeffc2

castellan/common/exception.py

@@ -43,9 +43,9 @@ class CastellanException(Exception):
             message_arg = self.message
         try:
             self.message = message_arg % kwargs
-        except Exception as e:
+        except Exception:
             if _FATAL_EXCEPTION_FORMAT_ERRORS:
-                raise e
+                raise
             else:
                 # at least get the core message out if something happened
                 pass