Added gws-theme-setup.php

Added this file which contains the after_theme_setup hook that is called
during each page load, after the theme is initialized. It is generally
used to perform basic setup, registration, and init actions for a theme.
Included gws-theme-setup.php

Add the gws-theme-setup.php file which contains the after_theme_setup
hook.
Update to theme support for custom backgrounds

Updated theme support feature for custom backgrounds to make use of new
functions.
Removed duplicate code

Removed duplicated add_theme_support code for custom header and
backgrounds.
Formatting changes

Minor changes to code formatting.