Mostly homepage template system changes

There's some widget CSS love here, but mostly these are changes to the homepage template system. 

For one, the organization of /homepages/ has been cleaned up, with CSS/LESS/JS files put into subdirectories. 

For another, the handling of upgrades from Largo 0.2 to 0.3 has been improved — no longer will sidebars vanish (among other issues).

To test, I:
- created a fresh install of wordpress and loaded in the Theme Unit Test data ( http://codex.wordpress.org/Theme_Unit_Test )
- enabled Largo 0.2 and set a number of Posts to be Homepage Featured and/or Top Story (and added Featured Images where needed)
- set the homepage top and homepage bottom values
- switch Largo from 0.2 to 0.3
- checked the appearance of the homepage and the Theme Options setting
- reset wp_options table and Largo version to 0.2 and moved on to the next permutation (six total: each of three homepage_top options combined with each of two homepage_bottom options)