Merge pull request #134 from javert03/2.2

Added explanation of columns in admin CSS
Fixes #132. Updating the Pages Docs

Fixing some inaccuracies and adding information about choosing page
types.
Small grammar fix

Makes this sentence a little clearer.
Adding content class to CP GUI Guide

This was added in 2.2 to make it easier for modules that want to go
full width.
Updating the CP GUI Guidelines

Adding in some 2.2 information, section nav, and correcting some
inaccurracies.

Fixes #117.
Adding Missing File::Upload() params