added double click action to zoom in

Signed-off-by: Pier-Luc Plante <pier-luc.plante.1@ulaval.ca>
added a client class

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
Merge branch 'master' of git://github.com/plpla/Ray-Cloud-Browser into pier-luc

Pier-Luc worked on a patch for zooming with double clicking.