Move required theme files to sage/resources

* Resolves issue with WP only looking one-level deep for templates #1870
* get_template_dir() and related functions now point to sage/resources
* Use collect() when assembling views paths
* Update tree in README

style.css

@@ -1,12 +0,0 @@
-/*
-Theme Name:         Sage Starter Theme
-Theme URI:          https://roots.io/sage/
-Description:        Sage is a WordPress starter theme.
-Version:            9.0.0-beta.2
-Author:             Roots
-Author URI:         https://roots.io/
-Text Domain:        sage
-
-License:            MIT License
-License URI:        http://opensource.org/licenses/MIT
-*/