Modularization and PEP8-ing changes

* Converted tabs to spaces for indentation
* Set up __main__.py for command line parser
* Set up argparse for CL parsing
* Tried to get the data structure the blog post categorization will use
going. Partial success, but category names get broken down into single
letters rather than using the whole category name as a string

TODO:
* Need to set up function defs to accept input variables so I don't
rely so much on global variables
* Finish the categories data structure