Updates Logging and User / Adds Venue

Fixes a little typo, but also uses a logging configuration most suitable for libraries. By using a null handler, we don't have to worry about interfering the developer's (the one using untappd-python) logging configurations.  We simply want to get a logger and log stuff, and not mess with any other part of the logging system.

References:
1. http://docs.python.org/2/howto/logging.html#configuring-logging-for-a-library
2. http://pieces.openpolitics.com/2012/04/python-logging-best-practices/

Secondly, I just added a change that fixes the call to get user info since it needs the username. I also reformatted it so that the __call__ is inherited from _Endpoint on both Beer and User (since they are essentially the same, this removes duplication).

Third, this adds an instance to get venue info.