Added dependency to ps.plone.fotorama.

Note: fotorama requires jQuery > 1.8, which is only available with
plone.app.jquery >= 1.8 and not available for Plone < 4.3.
Install new dependency ps.plone.fotorama.
Support galleria and fotorama slideshow. Currently only galleria is
active (hard coded in template). A backend setting will be added to
switch slideshows.