Add sessionstorage support to nag module

src/definitions/modules/nag.js

@@ -194,6 +194,10 @@ $.fn.nag = function(parameters) {
               window.localStorage.setItem(key, value);
               module.debug('Value stored using local storage', key, value);
             }
+            else if(settings.storageMethod == 'sessionstorage' && window.sessionStorage !== undefined) {
+              window.sessionStorage.setItem(key, value);
+              module.debug('Value stored using session storage', key, value);
+            }
             else if($.cookie !== undefined) {
               $.cookie(key, value, options);
               module.debug('Value stored using cookie', key, value, options);
@@ -210,6 +214,9 @@ $.fn.nag = function(parameters) {
             if(settings.storageMethod == 'localstorage' && window.localStorage !== undefined) {
               storedValue = window.localStorage.getItem(key);
             }
+            else if(settings.storageMethod == 'sessionstorage' && window.sessionStorage !== undefined) {
+              storedValue = window.sessionStorage.getItem(key);
+            }
             // get by cookie
             else if($.cookie !== undefined) {
               storedValue = $.cookie(key);
@@ -229,6 +236,9 @@ $.fn.nag = function(parameters) {
             if(settings.storageMethod == 'localstorage' && window.localStorage !== undefined) {
               window.localStorage.removeItem(key);
             }
+            else if(settings.storageMethod == 'sessionstorage' && window.sessionStorage !== undefined) {
+              window.sessionStorage.removeItem(key);
+            }
             // store by cookie
             else if($.cookie !== undefined) {
               $.removeCookie(key, options);