Fixed issue casued by recent angular upgrade and stateful filter, casued…

Fixed issue casued by recent angular upgrade and stateful filter, casued template vars in graph titles no update properly, angular was not updated in 1.8.1 so this does affect any released version, Closes #892

src/app/filters/all.js

@@ -56,9 +56,13 @@ define(['angular', 'jquery', 'lodash', 'moment'], function (angular, $, _, momen
   });
   });
 
 
   module.filter('interpolateTemplateVars', function(templateSrv) {
   module.filter('interpolateTemplateVars', function(templateSrv) {
-    return function(text) {
+    function interpolateTemplateVars(text) {
       return templateSrv.replaceWithText(text);
       return templateSrv.replaceWithText(text);
-    };
+    }
+
+    interpolateTemplateVars.$stateful = true;
+
+    return interpolateTemplateVars;
   });
   });
 
 
 });
 });