Various CSS fixes.

 * avatar image size in #following now fits the grid
 * move #pagination positioning over to "layout" partial
 * #footer font-size back to main CSS
Update to jQuery v.1.9.1.
Smoother transition to multi-column layout…

Along the way:

 * shorter transition-duration for .masonry-bricks (.4s instead of .7s)
 * set height and min-height for html, body, #container to allow setting a background for #container
 * move #container padding-bottom to #content
 * remove margin:0 auto for .centered-content #posts
 * fix and move #copyright styles over to "layout"-partial
Update jQuery version number in readme.