in tests, fix language change side effect

tests/automated/dayNames.js

@@ -18,12 +18,15 @@ describe('day names', function() {
 
   beforeEach(function() {
     affix('#cal');
-    moment.lang();
     settings = {
       now: moment(referenceDate).toISOString()
     };
   });
 
+  afterEach(function() {
+    moment.lang('en'); // reset moment's global language
+  });
+
   testableClasses.forEach(function(viewClass, index, viewClasses) {
     describe('when view is basicDay', function() {
       beforeEach(function() {

tests/automated/dayNamesShort.js

@@ -21,6 +21,10 @@ describe('short day names', function() {
     settings = { };
   });
 
+  afterEach(function() {
+    moment.lang('en'); // reset moment's global language
+  });
+
   testableClasses.forEach(function(viewClass, index, viewClasses) {
     describe('when view is ' + viewClass, function() {
       beforeEach(function() {