Associate Posts to Users

A user has_many posts, because they posted them.
Switch to Rspec <3
Add some tests around the post creation process
Add Paperclip
Render instantaneously

Don't wait for images to load, we can keep their dimensions and scale
them so we can position the grid right away.
Add the beginning notion of following a user
Style changes
Polish the homepage
All article types should link appropriately
Fix tests for paperclip images
Unify styling around the white box motif
Fix button active color

It should be a dark orange, not a dark blue