Accessibility - Include eviacam package in repositories

Ubuntu includes gnome-mousetrap, a head tracking software that take control over the mouse movements.
gnome-mousetrap is not compatible with a lot of cameras. eviacam is an alternative to gnome-mousetrap, with similar features.
Including both packages in the repositories, we managed to increase the number of cameras compatible with this kind of accessibility software.
Incorporate gnome-mousetrap and eviacam to the list of mobility applications in the "Preferred Applications" menu.
Enable multiple app selection in the "Accessibility" tab of the "Preferred Applications" menu.