Returns theme based on site

        Returns None and sets settings.THEME if able to find a theme object by site.

        Otherwise, returns False.

def theme_lookup(self):
        """
        Returns theme based on site

        Returns None and sets settings.THEME if able to find a theme object by site.

        Otherwise, returns False.
        """

        # check cache
        cache_key = 'theme:%s' % self.domain_unsplit
        theme = cache.get(cache_key)
        if theme:
            THEME.value = theme
            return None

        # check database
        if hasattr(self.site, 'themes'):
            try:
                themes = [theme.name for theme in self.site.themes.all()]
                THEME.value = themes[0]
                cache.set(cache_key, THEME.value, 5*60)
            except:
                return False
        return None