Rename to dir articles

Add to rename directory from article to articles.
Add index article url
Add ArticleIndexView
Add article detail
Add ArticleDetailView
Add Article get_absolute_url
Change article to articles in template_name
Add section list url
Add SectionListView
Add more detail test
Add section detail
Add SectionDetailView
Add Article app views

Add ArticleIndexView, ArticleDetailView, SectionListView, SectionDetailView
Add Section admin
Add Article admin
Add null/blank to Article.author
Add auto author field
Add article admin list niceities
Add Section and Article admin