Menu Customizer: remove (unused) code for displaying theme locations checkboxes, in favor of the theme locations section.

git-svn-id: https://plugins.svn.wordpress.org/menu-customizer/trunk@968413 b8457f37-d9ea-0310-8a92-e5e31aec5664
Menu Customizer: whitespace tweak in ajax file.

git-svn-id: https://plugins.svn.wordpress.org/menu-customizer/trunk@968417 b8457f37-d9ea-0310-8a92-e5e31aec5664