Spruce up the demo theme

There is some reorg here for performance improvements, and some sugar coz it's nice
Added README for general guidance

themes/demo/README.md

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+Demo Theme
+==========
+
+OctoberCMS demo theme that demonstrates the basic core functionality and utilizes the accompanying demo plugin. It is a great theme to copy when building a site from scratch. 
+
+The theme acts as a reference implementation for default component markup when distributing plugins.
+
+Have fun!
+
+## Clean up instructions
+
+If you clone this theme to use as a starting point. You may follow these instructions to clean up:
+
+1. Delete the `pages/ajax.htm` and `pages/plugins.htm` files.
+2. Delete the `partials/calcresult.htm` partial file.
+3. Delete the `partials/explain/` directory and contents.
+4. Delete the `content/placeholder/` directory and contents.
+
+## Combining CSS and JavaScript
+
+This theme doesn't combine assets for performance reasons. To combine the stylesheets, replace the following lines in the default layout.
+
+Uncombined stylesheets:
+
+    <link href="{{ 'assets/css/vendor.css'|theme }}" rel="stylesheet">
+    <link href="{{ 'assets/css/theme.css'|theme }}" rel="stylesheet">
+
+Combined stylesheets:
+
+    <link href="{{ [
+        '@framework.extras',
+        'assets/less/vendor.less',
+        'assets/less/theme.less'
+    ]|theme }}" rel="stylesheet">
+
+> **Note**: October also includes an SCSS compiler, if you prefer.
+
+Uncombined JavaScript:
+
+    <script src="{{ 'assets/vendor/jquery.js'|theme }}"></script>
+    <script src="{{ 'assets/vendor/bootstrap.js'|theme }}"></script>
+    <script src="{{ 'assets/javascript/app.js'|theme }}"></script>
+    {% framework extras %}
+
+Combined JavaScript:
+
+    <script src="{{ [
+        '@jquery',
+        '@framework',
+        '@framework.extras',
+        'assets/vendor/bootstrap.js',
+        'assets/javascript/app.js'
+    ]|theme }}"></script>
+
+> **Important**: Make sure you keep the `{% styles %}` and `{% scripts %}` placeholder tags as these are used by plugins for injecting assets.