Testing usage of Bootstrap layout in settings page.

Works somewhat to keep fluid layout with right sidebar. But is
overriding some built-in WP classes we need to keep.
Test custom minimal bootstrap.css build.

Removed responsive CSS and Bootstrap JS. Works but still maybe overkill?
Line up left-hand side of settings page container.

Had to override Bootstrap style.
Removed Bootstrap CSS. Now using custom CSS.

Uses classes that mimic built-in WP classes for post edit screen. It
felt clunky to use the post edit classes directly.
Merge pull request #1 from pderksen/settings-layout

Settings layout