Display the posts

Loop through the post list. This will display the title, content and
author of the post.
Add tags to post and only show excerpts

Showing the entire content of the blog posts took up too much space on
the screen. Space is saved by showing excerpts of the post and acts as a
teaser for the user. This allows them to make up their own mind when
determining whether to read a post.

It is also a general theme throughout most blogs. Other changes:

- Add date published to posts
- Add main tags
Add article tags to post loop

The article tag combined with the post_class tag automatically orders
the posts so they appear after eachother.