GH-2847 Adds Morden Theme as reader theme.

morden/sass/style-child-theme.scss

@@ -11,6 +11,7 @@ License URI: LICENSE
 Template: varia
 Text Domain: morden
 Tags: one-column, flexible-header, accessibility-ready, custom-colors, custom-menu, custom-logo, editor-style, featured-images, footer-widgets, rtl-language-support, sticky-post, threaded-comments, translation-ready, auto-loading-homepage, jetpack-global-styles, full-site-editing
+AMP: true
 
 This theme, like WordPress, is licensed under the GPL.
 Use it to make something cool, have fun, and share what you've learned with others.

morden/style-rtl.css

@@ -12,6 +12,7 @@ License URI: LICENSE
 Template: varia
 Text Domain: morden
 Tags: one-column, flexible-header, accessibility-ready, custom-colors, custom-menu, custom-logo, editor-style, featured-images, footer-widgets, rtl-language-support, sticky-post, threaded-comments, translation-ready, auto-loading-homepage, jetpack-global-styles, full-site-editing
+AMP: true
 
 This theme, like WordPress, is licensed under the GPL.
 Use it to make something cool, have fun, and share what you've learned with others.

morden/style.css

@@ -12,6 +12,7 @@ License URI: LICENSE
 Template: varia
 Text Domain: morden
 Tags: one-column, flexible-header, accessibility-ready, custom-colors, custom-menu, custom-logo, editor-style, featured-images, footer-widgets, rtl-language-support, sticky-post, threaded-comments, translation-ready, auto-loading-homepage, jetpack-global-styles, full-site-editing
+AMP: true
 
 This theme, like WordPress, is licensed under the GPL.
 Use it to make something cool, have fun, and share what you've learned with others.