Render our pages as a jinja template for fancy templating goodness.

def rstjinja(app, docname, source):
    """
    Render our pages as a jinja template for fancy templating goodness.
    """
    # Make sure we're outputting HTML
    if app.builder.format != 'html':
        return
    src = source[0]
    rendered = app.builder.templates.render_string(
        src, app.config.html_context
    )
    source[0] = rendered