Py3 compat: replace use of "unicode" (pwr/Solaar#32)

Generating "an unknown notification" type bailed out because of an unknown
feature type None. Since `isinstance(other, str)` is False for None, the script
will raise an exception on `isinstance(other, unicode)`.

There is no differentiation between `str` and `bytes` in Python 2, therefore
add another condition to `NamedInt.__eq__` to catch unknown types (like
`bytes`).
Merge pull request #37 from Lekensteyn/py3-compat

Py3 compat: replace use of "unicode" (pwr/Solaar#32)

The `u''` syntax fails in Python 3.2; will fix is_string after the merge.