Generates an invalid code block when code has an empty line

[vzvu3k6k]

Let fixture/test.js has the following content:

console.log("foo");

console.log("bar");

This plugin will expand [import](fixtures/test.js) into:

> [test.js](fixtures/test.js)
```js
console.log("foo");

console.log("bar");

Gitbook renders it as:

`````` html
<blockquote>
<p><a href="fixtures/test.js">test.js</a>
```js
console.log(&quot;foo&quot;);</p>
</blockquote>
<p>console.log(&quot;bar&quot;);</p>
<pre><code>

These pages are affected by this issue:

• http://azu.gitbooks.io/javascript-plugin-architecture/content/ja/jQuery/index.html
• http://azu.gitbooks.io/javascript-plugin-architecture/content/ja/ESLint/index.html

[azu]

@vzvu3k6k Thanks for report. This isssue was fixed in #4

[vzvu3k6k]

:+1: