fix(registry): create /deis/cache etcdctl dir

Author: mboersma

deisctl/units/deis-registry.service

@@ -4,6 +4,7 @@ Description=deis-registry
 [Service]
 EnvironmentFile=/etc/environment
 TimeoutStartSec=30m
+ExecStartPre=-/usr/bin/etcdctl mkdir /deis/cache >/dev/null 2>&1
 ExecStartPre=/bin/sh -c "IMAGE=`/run/deis/bin/get_image /deis/registry` && docker history $IMAGE >/dev/null 2>&1 || docker pull $IMAGE"
 ExecStartPre=/bin/sh -c "docker inspect deis-registry >/dev/null 2>&1 && docker rm -f deis-registry || true"
 ExecStart=/bin/sh -c "IMAGE=`/run/deis/bin/get_image /deis/registry` && docker run --name deis-registry --rm -p 5000:5000 -e EXTERNAL_PORT=5000 -e HOST=$COREOS_PRIVATE_IPV4 $IMAGE"