STORAGE_ROOT needs to be readable for nginx to have access

setup/start.sh

@@ -79,6 +79,7 @@ fi
 if [ ! -d $STORAGE_ROOT ]; then
 	mkdir -p $STORAGE_ROOT
 fi
+chmod o+rx $STORAGE_ROOT
 if [ ! -f $STORAGE_ROOT/mailinabox.version ]; then
 	setup/migrate.py --current > $STORAGE_ROOT/mailinabox.version
 	chown $STORAGE_USER.$STORAGE_USER $STORAGE_ROOT/mailinabox.version