Modernize the bundle, add parser implementation choice, and improve doc.

MarkdownParserInterface.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Knplabs\Bundle\MarkdownBundle;
+
+interface MarkdownParserInterface
+{
+    /**
+     * Converts text to html using markdown rules
+     *
+     * @param string $text plain text
+     * @return string rendered html
+     */
+    function transform($text);
+}