use systemd socket-activation by default

	modified:   contrib/init/systemd/docker.service
	renamed:    contrib/init/systemd/socket-activation/docker.socket -> contrib/init/systemd/docker.socket
	deleted:    contrib/init/systemd/socket-activation/docker.service

Docker-DCO-1.1-Signed-off-by: Lokesh Mandvekar <lsm5@fedoraproject.org> (github: lsm5)

contrib/init/systemd/docker.service

@@ -4,7 +4,7 @@ Documentation=http://docs.docker.com
 After=network.target
 
 [Service]
-ExecStart=/usr/bin/docker -d
+ExecStart=/usr/bin/docker -d -H fd://
 Restart=on-failure
 LimitNOFILE=1048576
 LimitNPROC=1048576

contrib/init/systemd/socket-activation/docker.service

@@ -1,13 +0,0 @@
-[Unit]
-Description=Docker Application Container Engine
-Documentation=http://docs.docker.com
-After=network.target
-
-[Service]
-ExecStart=/usr/bin/docker -d -H fd://
-Restart=on-failure
-LimitNOFILE=1048576
-LimitNPROC=1048576
-
-[Install]
-WantedBy=multi-user.target