Expand IE testing

Now that our tests are using jQuery 1.7.2 we can run our tests on
IE8 automatically.

Gruntfile.js

@@ -98,6 +98,10 @@ module.exports = function (grunt) {
           urls: testUrls,
           testname: 'QUnit test for Select2',
           browsers: [
+            {
+              browserName: 'internet explorer',
+              version: '8'
+            },
             {
               browserName: 'internet explorer',
               version: '9'
@@ -106,6 +110,10 @@ module.exports = function (grunt) {
               browserName: 'internet explorer',
               version: '10'
             },
+            {
+              browserName: 'internet explorer',
+              version: '11'
+            },
 
             {
               browserName: 'firefox'