Ashwin/ Implement MVC patterns for Encyclopedia web app

[MrHaikuSwan]

This Commit:

• Creates Article Model representing title (string), author(string), date(date), and content(text)
• Creates ArticlesController exposing CRUD operations upon Article
• Creates index.html.erb homepage to view all encyclopedia articles
• Implements search bar on homepage to filter articles by query substring
• Creates New Article and Edit Article pages to create and update articles

Notes:
The search functionality only checks for substring existence in the title or content of each article -- AND/OR queries by term are not supported.