test/knownRegions.js let -> var (quick fix) (#18)

needed to pass on older Node.js versions
diff --git a/test/knownRegions.js b/test/knownRegions.js
index 6d3144c..08ce454 100644
--- a/test/knownRegions.js
+++ b/test/knownRegions.js
@@ -71,10 +71,10 @@
   },
 
   'should do nothing if named region does not exist in knownRegions': function (test) {
-    let numberOfRegions = project.pbxProjectSection()[project.getFirstProject()['uuid']]['knownRegions'].length;
+    var numberOfRegions = project.pbxProjectSection()[project.getFirstProject()['uuid']]['knownRegions'].length;
 
     project.removeKnownRegion('Korean');
-    let newNumberOfRegions = project.pbxProjectSection()[project.getFirstProject()['uuid']]['knownRegions'].length;
+    var newNumberOfRegions = project.pbxProjectSection()[project.getFirstProject()['uuid']]['knownRegions'].length;
     test.equal(numberOfRegions, newNumberOfRegions);
     test.done();
   },