Fix broken extract_strings

lib/commonplace.js

@@ -264,7 +264,7 @@ function extract_l10n() {
     var context = new (require('./extract_l10n').L10nContext)();
     var src_dir = info.src_dir();
 
-    _check_version(src_dir, undefined, undefined, function() {
+    check_version(src_dir, undefined, undefined, function() {
         console.error('No Commonplace installation found.');
         process.exit(1);
     });