Update pagination with a simpler setup

I noticed WooCommerce's pagination system was nice and simple, and it also corresponds pretty well to [paginate_links() on the Codex](http://codex.wordpress.org/Function_Reference/paginate_links).

I tried it out with a custom version of Bones on a site I'm working on, and on a fresh copy with the [Theme Unit Test](http://codex.wordpress.org/Theme_Unit_Test), and this pagination system seems it work fine, including custom post type archives, etc.

Since the markup does change a bit I also included the CSS in library/scss/_base.scss to make it look decent. The styling is a bit more subdued and I put in the left & right arrow characters instead of the "<<" & ">>".

I did not include the rendered CSS (library/style.css), because whatever version of Sass CodeKit is using wanted to change every line, putting braces on the same line as the last declaration, etc.

Signed-off-by: Gabriel Luethje <gabriel@thefstopdesign.com>