Version 0.4.1 breaks on Python 2.7 because of byte representation

[khuumi]

Your newest changes cause things to break with our Python 2.7 codebase when we are sending bytes. Python 2.7 bytes are type str so when you do the check on wsgiadapter.py#L112 it thinks what is being passed in is a string, tries to encode it as UTF-8 and then fails.

[seanbrant]

@khuumi Can you provide failing example code? That would help me write a testcase and get a fix released.