Update clone link refs MongoEngine/mongoengine#20

Author: rozza

_includes/themes/mongoengine/frontpage.html

@@ -149,7 +149,7 @@ <h2><a name="source"></a>Source</h2>
       <p>The source code is available for download under the MIT
          License over at <a href="http://github.com/mongoengine/mongoengine">GitHub</a>. To
          checkout the latest version using git, clone the mainrepository:</p>
-       <p><code>git clone git://github.com/mongoengine/mongoengine.git</code></p>
+       <p><code>git clone https://github.com/MongoEngine/mongoengine.git</code></p>
     </div>
     <div class="span5">
       <h3 class="first">Contributing</h3>