cripts/check_site.lua: print paths separated by '.' rather than '/'

Using slashs instead of dots is a bit unexpected, and as long as we're not
going for full-blown JSONPath, neither is more correct than the other.

scripts/check_site.lua

@@ -63,7 +63,7 @@ end
 
 
 local function path_to_string(path)
-	return table.concat(path, '/')
+	return table.concat(path, '.')
 end
 
 local function array_to_string(array)