Templates

Let's leave this open for a little bit while I tackle a few things:

- document layout chain better in the layouts section (started in on this on the content-base.html section)
- ~~move layouts section to docs, probably rename to avoid conflict with Less layout docs~~
- rename content_block to just block?
- ~~rename base layout .html files so visually it appears there are only a few layouts to choose~~
- ~~rename section_vars to section~~
- look into relative imports: http://stackoverflow.com/questions/8512677/how-to-include-a-template-with-relative-path-in-jinja2
- remove scoped from layout blocks? (not exactly sure if this is needed but i added it to all, would be nice to remove them if not needed)