I have changed /etc/default/docker with DOCKER_OPTS=\"-H tcp://127.0.0.1:2375 -H unix:///var/run/docker.sock\" (docker version 1.4.1 in ubuntu 14.0
/etc/default/docker
DOCKER_OPTS=\"-H tcp://127.0.0.1:2375 -H unix:///var/run/docker.sock\"
I had the same issue.
Ubuntu 14.10 uses systemd instead of sysv-init/upstart. Maybe you should look into /lib/systemd/system/docker.service to change the options.
systemd
sysv-init/upstart
/lib/systemd/system/docker.service