Allow specifying files via $min_symlinks paths

If you have an alias/symlink like "//~name" => "/full/path", then you can
now serve with the more logical URL http://example.com/min/?f=~name/foo.css

Fixes #137

lib/Minify/CSS/UriRewriter.php

@@ -48,8 +48,8 @@ class Minify_CSS_UriRewriter {
         );
         self::$_currentDir = self::_realpath($currentDir);
         self::$_symlinks = array();
-        
-        // normalize symlinks
+
+        // normalize symlinks in order to map to link
         foreach ($symlinks as $link => $target) {
             $link = ($link === '//')
                 ? self::$_docRoot