Update media.html following audio and video html transformation fixes

- Remove "src" from audio and video tags as <source> is already used
- If autoplay is true, set autoplay="autoplay" in audio and video tags,
  if autoplay is false, remove the attribute
Add xsl/test/ to automated test suite

Use xsltproc to transform xsl/test/*.cnxml files with
xsl/cnxml-to-html5.xsl and compare with xsl/test/*.html files
Merge pull request #63 from Connexions/more-tests

Add xsl/test/ to python automated test suite