title: How to get application root path in GAE
body: <p>I am using Jinja2 templates for my GAE Python application. Actually there are a couple of small applications inside one project. They are, for example, blog and site. So, the first one is for blog and the second one is for site =). I have this folders structure:</p>
  
  <pre><code>/
    /apps
      /blog
      /site
  /templates
    /blog
    /site
  </code></pre>
  
  <p>I also have a code for accessing templates folder for each application. It looks like this:</p>
  
  <pre><code>template_dirs = []
  template_dirs.append(os.path.join(os.path.dirname(__file__), 'templates/project'))
  </code></pre>
  
  <p>Of course, it doesn't work as it's wrong. It returns a string like this:
      base/data/home/apps/myapplication/1.348460209502075158/apps/project/templates/project</p>
  
  <p>And I need it to return a string like this:
      base/data/home/apps/myapplication/1.348460209502075158/apps/templates/project
  How can I do that using absolute paths, not relative? I suppose I need to get the root of the my whole GAE project some way.
  Thanks!</p>