Massive commit. Main activity was adding the "octo" theme, which is the style
and layout of octopress 2.0's default "classic" theme.

Several things were factored down along the way around layout. the theme layout
".html" page is mostly responsible for structure, and the functions have been
separated for the themes into post/page sidebar and main areas.

These are shared between octo and the base_bootstrap theme. The "twitter" theme is
behind and will be caught up later once the dust settles.