Use en_US as default locale for components to avoid problems where test cluster browsers send different locales

svn changeset:16648/svn branch:6.5

tests/src/com/vaadin/tests/components/AbstractComponentTest.java

         options.put("zh_CN", Locale.SIMPLIFIED_CHINESE);
         options.put("fr_FR", Locale.FRANCE);
 
-        createSelectAction("Locale", category, options, "-", localeCommand,
+        createSelectAction("Locale", category, options, "en_US", localeCommand,
                 null);
     }