Added `pagination.has_posts` template property.
Changes around built-in pages and themes:
- A theme's default template directory is added, if it exists.
- Built-in pages/templates have been replaced with a built-in theme.
- The built-in theme is used if not local theme is found.
- This makes it possible to use some partial templates in the built-in pages.
- This also removes the need from creating default templates with `chef init`.
Added `.md` and `.textile` to the default auto-formats.
Fixed CHANGELOG typos.
Fixed quickstart in README.