Load mathjax with its Safe extension

Author: jasongrout

jupyter_notebook/static/phosphor-notebook/index.html

@@ -6,7 +6,7 @@
     <link rel="stylesheet" href="components/codemirror/lib/codemirror.css">
     <script src="components/marked/marked.min.js"></script>
     <script src="/static/components/requirejs/require.js"></script>
-    <script src="/static/components/MathJax/MathJax.js?config=TeX-AMS_HTML-full&delayStartupUntil=configured"></script>
+    <script src="/static/components/MathJax/MathJax.js?config=TeX-AMS_HTML-full,Safe&delayStartupUntil=configured"></script>
     <link href="components/phosphor/dist/phosphor.css" rel="stylesheet" type="text/css">
     <!--<link href="build/index.css" rel="stylesheet" type="text/css">-->
     <script src="components/phosphor/dist/phosphor.js"></script>