Remove update-checker dependency update-checker is a module that checks PyPI for updates to a given package, and praw uses the module to notify the user when it's out of date. This isn't very helpful to users who can't do anything about it when using a packaged version of praw, so this patch removes that dependency. Luckily, praw silently skips this check when update-checker fails to import, so nothing needs to be done but remove it from setup.py and egg-info.
