Added an equation example to test the ..math:: directive.

test.ipynb

@@ -135,6 +135,12 b''
      "prompt_number": 4
     },
     {
+     "cell_type": "markdown",
+     "source": [
+      "$e^{i\\pi} + 1 = 0$"
+     ]
+    },
+    {
      "cell_type": "code",
      "collapsed": true,
      "input": [],