Fix sed replacement command in Ubuntu's install_docker

The 's' command wasn't closed properly. This was fixed in kolla repo
before it was decided that the dev env should go in kolla-ansible.

Change-Id: Ia1434ebb276f0fc76bf88fe386b8e9527133ce4d

contrib/dev/vagrant/bootstrap.sh

@@ -118,7 +118,7 @@ EOF
         echo "deb https://apt.dockerproject.org/repo ubuntu-wily main" > /etc/apt/sources.list.d/docker.list
         apt-get update
         apt-get -y install docker-engine
-        sed -i -r "s,(ExecStart)=(.+),\1=/usr/bin/docker daemon --insecure-registry ${REGISTRY} --registry-mirror=http://${REGISTRY}|" /lib/systemd/system/docker.service
+        sed -i -r "s|(ExecStart)=(.+)|\1=/usr/bin/docker daemon --insecure-registry ${REGISTRY} --registry-mirror=http://${REGISTRY}|" /lib/systemd/system/docker.service
     else
         echo "Unsupported Distro: $DISTRO" 1>&2
         exit 1