'Manage the driver\'s local image cache.
Some drivers chose to cache images for instances on disk. This method
is an opportunity to do management of that cache which isn\'t directly
related to other calls into the driver. The prime example is to clean
the cache and remove images which are no longer of interest.
:param all_instances: nova.objects.instance.InstanceList'

def manage_image_cache(self, context, all_instances):

    pass
