Implement article parser for XML articles

[vivi]

Hi all,

This parses the new articles, by calling parse_article(file_path). Notes for backend:

• The model OR the code that adds articles to the database will have to get updated to match what the article parser gives back, in terms of fields.
• To just see it run, type python parse_article.py -f <FILENAME> or python parse_article.py -d <DIRECTORY>

It's been fun working with y'all!