Volumed data setup changed to allow #1759

- Volumed subfolder now created up in the ENTRYPOINT script, this way
  they are created before S6 even starts making VOLUME.
- The subfolder will be created during VOLUME creation too as ENTRYPOINT
  script will be run before /bin/true
- SSH Keys will now be created on a single key basis not replying on the
  existence of /data/ssh folder

docker/s6/gogs/setup

@@ -1,11 +1,7 @@
 #!/bin/sh
 
-if ! test -d /data/gogs; then
-    mkdir -p /data/gogs/data /data/gogs/conf /data/gogs/log /data/git
-fi
-
 if ! test -d ~git/.ssh; then
-    mkdir ~git/.ssh
+    mkdir -p ~git/.ssh
     chmod 700 ~git/.ssh
 fi