Set encoding of message.py to utf8.

The file contains an integral sign which breaks compilation on python2.7+
when no encoding is set.
Remove unnecessary dependencies.

cherrypy is only used for the example so keeping it in the development
mode should be fine.

argparse and importlib are shipped with python2.7+
Merge pull request #53 from teh/master

Minor cleanups of dependencies and encoding for python2.7