Update sauce tests for supported versions

Gruntfile.js

@@ -141,12 +141,15 @@ module.exports = function(grunt) {
             {browserName: 'firefox', version: '3.6'},
             {browserName: 'safari', version: 7, platform: 'OS X 10.9'},
             {browserName: 'safari', version: 6, platform: 'OS X 10.8'},
-            {browserName: 'opera'},
+            {browserName: 'safari', version: 5},
+            {browserName: 'opera', version: 12},
+            {browserName: 'opera', version: 11},
             {browserName: 'internet explorer', version: 11, platform: 'Windows 8.1'},
             {browserName: 'internet explorer', version: 10, platform: 'Windows 8'},
             {browserName: 'internet explorer', version: 9, platform: 'Windows 7'},
             {browserName: 'internet explorer', version: 8, platform: 'XP'},
-            {browserName: 'internet explorer', version: 7, platform: 'XP'}
+            {browserName: 'internet explorer', version: 7, platform: 'XP'},
+            {browserName: 'internet explorer', version: 6, platform: 'XP'}
           ]
         }
       }

README.markdown

@@ -323,6 +323,8 @@ Handlebars has been designed to work in any ECMAScript 3 environment. This inclu
 Older versions and other runtimes are likely to work but have not been formally
 tested.
 
+[![Selenium Test Status](https://saucelabs.com/browser-matrix/handlebars.svg)](https://saucelabs.com/u/handlebars)
+
 Performance
 -----------