Add in pagination with a simple static widget.
Intelligently hide/show post links depending on the number of pages.
Hide the pagination widget if there's less than one page of posts.
Clean up the CSS, removed numbered links.
Actually hook up pagination.

This probably should've been multiple commits, but oh well. We change
showPaginatedPosts to take a page router, and change most of the
routes to include a page number parameter (if it's 1, the /page/1 is
just omitted).
Make the page buttons a bit bigger and shrink their top margins.
Merge branch 'pagination' (closes #14)