bug(systemd): fix dependencies

This commit does several things:
* Refactor After and Requires to list all units on one line
* Make seed-registry job dependent upon deis-registry
* Make controller dependent on (and wait for) Builder
* Make all services only start after etcd

closes #706, #708

Author: carmstrong

systemd/deis-controller.service

@@ -1,13 +1,11 @@
 [Unit]
 Description=deis-controller
-After=docker.service
-Requires=docker.service
-Requires=docker-tcp.socket
-Requires=etcd.service
+Requires=docker.service docker-tcp.socket etcd.service deis-builder.service
+After=docker.service etcd.service deis-builder.service
 
 [Service]
 ExecStart=/bin/bash -c '/usr/bin/docker start -a deis-controller || /usr/bin/docker run --name deis-controller -p 8000:8000 -e PUBLISH=8000 -e HOST=172.17.8.100 -e ETCD=172.17.8.100:4001 deis/controller'
 ExecStop=/usr/bin/docker stop deis-controller
 
 [Install]
-WantedBy=multi-user.target
+WantedBy=multi-user.target