Fix UnicodeDecodeError in Python 2 with Object Macros - #28

This fixes a bug for Python 2 where a Python object macro was unable to return a Unicode string, due to the Python macro handler casting all return values as str() type, which in Python 2, assumes ASCII, and it would raise a UnicodeDecodeError.

Instead the return value is casted to six.text_type which will be unicode in Python 2 and str in Python 3.

The following RiveScript example code demonstrates the original problem and that this change fixes it:

> object wiki python
    import re
    import requests

    res = requests.get("http://bulbapedia.bulbagarden.net/wiki/Umbreon_(Pok%C3%A9mon)")
    m = re.search(r': <b>(.+?)</b> <i>Blacky</i>', res.text)

    if m:
        name = m.group(1)
        return name
    return "No match"
< object

+ test
- Result: <call>wiki</call>

Expected result:

You> test
Bot> Result: ブラッキー