Thanks @GuZ your tip helped me solve the issue on Ubuntu 14.04
I stopped the clloabora dock by
docker ps (to get the id)
docker stop [id]
docker rm [id]
then changed /etc/default/docker
# Use DOCKER_OPTS to modify the daemon startup options.
DOCKER_OPTS="--storage-driver=devicemapper"
restarted docker
and started collabora again which downloaded a new image and is running perfect now
for big production sites it’s maybe worth do fix the aufs problem or to propperly configure devicemapper like described here: https://docs.docker.com/engine/userguide/storagedriver/device-mapper-driver/, for personal use about fix should be fine