Remove unnecessary files

[enderandpeter]

There are some committed files that need not be in the repo, namely the __pycache__ folder and the .idea folder. They should be ignored by local gitignore rules because they are created by programs that not every developer is necessarily using. The .idea folder comes from PyCharm, and although it's the IDE used in the tutorial, a developer might be using some other editor. Also, the contents of the folder tend to be geared towards a particular environment. I'm not sure what made the __pycache__ folder, but its contents are not required. At any rate, these are the only files that do not pertain directly to the project and are created by programs on the user's machine.