Slightly improve the rollingstats class demo.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Add the rollingstat class demo html files.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Slightly improve the simpletracker demo.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Add the simpletracker demo html files.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>