Endpoint decorator unicode exception

This seems to fix it.  @manthey Maybe you can suggest a test case where `repr` is needed.  It is a bit complicated by the fact that the value is an object.
It doesn't look like it.
```
28: ======================================================================
28: ERROR: test_endpoint_exception_ascii (tests.cases.rest_decorator_test.testEndpointDecoratorException)
28: ----------------------------------------------------------------------
28: Traceback (most recent call last):
28:   File "tests/base.py", line 123, in setUp
28:     addr = ':'.join(map(str, mockSmtp.address))
28: TypeError: argument 2 to map() must support iteration
```