fix(*): etcdctl and docker history commands eat error output

These errors are benign, but confusing to new users.

TESTING: reprovision a cluster (due to changes in cloud config), build
components from source, `make run`, and ensure that there are no
confusing errors in the output

```console
$ vagrant destroy -f && vagrant up
$ make build run
```

```
$ fleetctl status deis-router.1
< snipped... >
Jul 23 19:18:53 deis-1 systemd[1]: Starting deis-router...
Jul 23 19:18:54 deis-1 systemd[1]: Started deis-router.
Jul 23 19:19:06 deis-1 sh[4546]: router: waiting for confd to write initial templates...
Jul 23 19:19:11 deis-1 sh[4546]: Starting Nginx...
Jul 23 19:19:11 deis-1 sh[4546]: deis-router running...
```

Author: carmstrong

bin/boot

@@ -16,7 +16,7 @@ export ETCD_PATH=${ETCD_PATH:-/deis/controller}
 export ETCD_TTL=${ETCD_TTL:-10}
 
 # wait for etcd to be available
-until etcdctl --no-sync -C $ETCD ls >/dev/null; do
+until etcdctl --no-sync -C $ETCD ls >/dev/null 2>&1; do
 	echo "waiting for etcd at $ETCD..."
 	sleep $(($ETCD_TTL/2))  # sleep for half the TTL
 done

systemd/deis-controller.service

@@ -6,8 +6,8 @@ After=deis-logger.service
 [Service]
 EnvironmentFile=/etc/environment
 TimeoutStartSec=20m
-ExecStartPre=/bin/sh -c "IMAGE=`/run/deis/bin/get_image /deis/controller`; docker history $IMAGE >/dev/null || docker pull $IMAGE"
-ExecStartPre=/bin/sh -c "docker inspect deis-controller >/dev/null && docker rm -f deis-controller || true"
+ExecStartPre=/bin/sh -c "IMAGE=`/run/deis/bin/get_image /deis/controller`; docker history $IMAGE >/dev/null 2>&1 || docker pull $IMAGE"
+ExecStartPre=/bin/sh -c "docker inspect deis-controller >/dev/null 2>&1 && docker rm -f deis-controller || true"
 ExecStart=/bin/sh -c "IMAGE=`/run/deis/bin/get_image /deis/controller` && docker run --name deis-controller --rm -p 8000:8000 -e PUBLISH=8000 -e HOST=$COREOS_PRIVATE_IPV4 --volumes-from=deis-logger $IMAGE"
 ExecStopPost=/usr/bin/docker stop deis-controller