Modify Post route to allow for SEO slug suffix.
Use Post model for getting URL rather than having logic for building the url in the template.
Use slugs in post URLs, redirecting to slugged URL if not specified.
Make sure we 301 redirect to the slug URL.
When saving a post, use the post url on the model.
Merge pull request #69 from bobbyshaw/feature/post-slugs

Add post slugs for SEO.