fix: 3.x compat, cdata & django tags in script

django tags in style and script tags were not converting
because of the difference in the underlying html parser. sufficent to
check if soup is non-empty versus checking if soup.body is non-null.

in escape_html_except_for_dynamic iterator over soup.contents instead of
soup.body.children

fixed inconsistencies in cdata content indentation after content is
converted to django

fix relative import bug with python 3. Explicitly specify the relative
directory instead of python searching in sys.path