Remove .lock files with Makefile distclean action

Makefile

@@ -102,6 +102,7 @@ distclean: clean
 	rm -rf node_modules
 	rm -rf js/vendor
 	rm -rf js/node_modules
+	rm -f composer.lock package-lock.json
 
 # Builds the source package for the app store, ignores php tests, js tests
 # and build related folders that are unnecessary for an appstore release