Added course description parser

Added the parser for extracting data from http://coursecatalog.web.cmu.edu pages to JSON files.
I know this is a script, so it's probably only ever going to be run as a command line executable, but do you want to check to make sure of this before actually running any code? Most Python scripts use something like

```python
if __name__ == "__main__":
    # code when running interactively
```

The global variable `__name__` is set when the program is running in ["top-level script environment"][1].

This way if we ever want or need to call the code from another file using an `import` statement, only the appropriate code runs.

[1]: https://docs.python.org/2/library/__main__.html