reimport HTML in different section

Explicitely reimport HTML from IPython.display when we change section
avoid references to fiel out of directory

request for packaging, it would be nice for example not to reference
files outside of exampel directory
copy ../../_static/logo.png in logo/logo.png
use subfolder for demo purpose of targetting subfolder in
demo notebook
Merge pull request #3060 from Carreau/fix-ex.0.13.x

Fix Exampel for 0.13.x