Adds option to have the sidebar on the bottom
A lot of features added. Also added link posts.

- ADD: Link post type
- ADD: Custom header
- ADD: Title color customization
- ADD: Body color customization
- ADD: Custom header images

- REMOVE: Ability to push sidebar to the bottom (left and right take higher priority)
It's 4am and I've made 3 post types on one branch. Woops.
Merge branch 'posts/link'