Remove dependency on Sass

- Convert *.sass files to vanilla CSS
- Start using CSS variables
- Add PHP minifier

libs/minify/src/Exception.php

@@ -0,0 +1,20 @@
+<?php
+/**
+ * Base Exception
+ *
+ * @deprecated Use Exceptions\BasicException instead
+ *
+ * @author Matthias Mullie <minify@mullie.eu>
+ */
+namespace MatthiasMullie\Minify;
+
+/**
+ * Base Exception Class
+ * @deprecated Use Exceptions\BasicException instead
+ *
+ * @package Minify
+ * @author Matthias Mullie <minify@mullie.eu>
+ */
+abstract class Exception extends \Exception
+{
+}