only enable pan-zoom controls for images (#3699)
only enable pan-zoom controls for images (#3699)


jelliotartz/Panoptes-Front-End,amyrebecca/Panoptes-Front-End,amyrebecca/Panoptes-Front-End,jelliotartz/Panoptes-Front-End,jelliotartz/Panoptes-Front-End,amyrebecca/Panoptes-Front-End,zooniverse/Panoptes-Front-End