Misc (#120)

* add example docker override (one which would disable the mail container)
* move some config options from docker-compose into the default conf
* add missing depends_on

core/defaultconfigs/server.py

@@ -10,7 +10,9 @@ kcconf.configkopano({
         'attachment_path': "/kopano/data/attachments/",
         'user_plugin': "ldap",
         'server_listen': "*:236",
-        'server_listen_tls': "*:237"
+        'server_listen_tls': "*:237",
+        'sync_gab_realtime': "no",
+        'kdoidc_initialize_timeout': "360"
     }
 })