Finnally, the archives page.

This design was highly inspired by
http://bootsnipp.com/snippets/featured/timeline-21-with-images-and-responsive.
I made some tiny modifications:
1. remove the img header, add a grey background timeline-heading.
2. add tags/categories to footer
3. modify some paddings and margins.
4. refine link_attribute function, add a third param to determine
whether generate posts' length to output link.