title: python/jinja2 issue rendering template containing unicode characters
body: <p>I have the following code which uses the jina2 engine to render some html.</p>
  
  <pre><code>env = jinja2.Environment(loader=templateLoader, autoescape=True,trim_blocks=True)
  template = env.get_template("template.html")
  ...
  data = {
      'title' : 'test'
  }
  html = template.render(data)
  </code></pre>
  
  <p>In the template, if i add the following javascript line, the rendering fails (Notice the superscript):</p>
  
  <pre><code>var x2 = 'x²';
  </code></pre>
  
  <p>The exception is:</p>
  
  <pre><code>File "C:\python_2.7\lib\site-packages\jinja2\filters.py", line 747, in do_mark_safe
  File "C:\python_2.7\lib\site-packages\markupsafe\__init__.py", line 74, in __new__
  UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 6689: ordinal not in range(128)
  </code></pre>
  
  <p>How can i use an html template containing non-ascii characters with jinja2/python?</p>