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

resources/views/partials/content-single.blade.php

@@ -9,5 +9,5 @@
   <footer>
     {!! wp_link_pages(['echo' => 0, 'before' => '<nav class="page-nav"><p>' . __('Pages:', 'sage'), 'after' => '</p></nav>']) !!}
   </footer>
-  @php(comments_template('/resources/views/partials/comments.blade.php'))
+  @php(comments_template('/partials/comments.blade.php'))
 </article>