Closes #299.

Due to the mixed testing between Python 2 and 3 and different string
implementations, there's no easy way to test Unicode stuff.

Closes #300.

The original implementation used str.encode() on input and str.decode() on
output. However this would cause UnicodeDecodeError since certain characters
can't be encoded / decoded in ASCII.

The new solution is to use unicode() on all input strings and output UTF-8
encoded strings. This makes the assumption that the shell can handle UTF-8
strings.

The original implementation used str.encode() on input and str.decode() on
output. However this would cause UnicodeDecodeError since certain characters
can't be encoded / decoded in ASCII.

The new solution is to use unicode() on all input strings and output UTF-8
encoded strings. This makes the assumption that the shell can handle UTF-8
strings.