add Kdav (#83)

* add a kdav image
* do not install composer into the docker image
instead use a multi stage build that copies the resulting directory into the final image
* set default version in compose

resolves #54

web/kweb.cfg

@@ -159,6 +159,18 @@
     }
     folderish /caldav
 
+    proxy /kdav/ kopano_kdav:80 {
+        transparent
+        keepalive 0
+        fail_timeout 10s
+        try_duration 30s
+    }
+
+    redir 301 {
+        /.well-known/carddav /kdav/
+        /.well-known/caldav  /kdav/
+    }
+
     proxy /ldap-admin/ ldap-admin:80 {
         without /ldap-admin
         transparent