Use the 2.0.0 Alpha version of Modular Scale

I ran into a problem where using any of the ratio variables
($golden, $fifth, etc.) threw a compiler error.

It took me a while to realize the Gemfile wasn't using the
proper version. Those variables were introduced in 2.0.0.
Section compass plugins differently in base partial.

I think this is a better approach to importing compass plugins;
putting them in their own modular sections that can be easily
swapped around.
Add CSS3 Compass module for later.
Add skeleton of the css – styling coming soon!
Section off Compass/Imports and Variables in base partial.

Also add some starting variables for typography.
Modify grid layout and modular scale values
Import Droid Sans font from Google (_base.scss)

I should've done this two commits ago.
Add Structure section with grid mixins (screen)
Setup styling for main elements.
Update Index to reflect css changes