Upgrade MathJax to 2.4.

Several IE bugs have been fixed in 2.4.

cms/static/coffee/spec/main.coffee

@@ -47,7 +47,7 @@ requirejs.config({
         "URI": "xmodule_js/common_static/js/vendor/URI.min",
         "mock-ajax": "xmodule_js/common_static/js/vendor/mock-ajax",
 
-        "mathjax": "//cdn.mathjax.org/mathjax/2.2-latest/MathJax.js?config=TeX-MML-AM_HTMLorMML-full&delayStartupUntil=configured",
+        "mathjax": "//cdn.mathjax.org/mathjax/2.4-latest/MathJax.js?config=TeX-MML-AM_HTMLorMML-full&delayStartupUntil=configured",
         "youtube": "//www.youtube.com/player_api?noext",
         "tender": "//api.tenderapp.com/tender_widget",
 

cms/static/coffee/spec/main_squire.coffee

@@ -41,7 +41,7 @@ requirejs.config({
         "domReady": "xmodule_js/common_static/js/vendor/domReady",
         "URI": "xmodule_js/common_static/js/vendor/URI.min",
 
-        "mathjax": "//cdn.mathjax.org/mathjax/2.2-latest/MathJax.js?config=TeX-MML-AM_HTMLorMML-full&delayStartupUntil=configured",
+        "mathjax": "//cdn.mathjax.org/mathjax/2.4-latest/MathJax.js?config=TeX-MML-AM_HTMLorMML-full&delayStartupUntil=configured",
         "youtube": "//www.youtube.com/player_api?noext",
         "tender": "//api.tenderapp.com/tender_widget.js"
 

cms/static/require-config.js

@@ -74,7 +74,7 @@ require.config({
             // so that require doesn't fall over
             "js/src/tender_fallback"
         ],
-        "mathjax": "//cdn.mathjax.org/mathjax/2.2-latest/MathJax.js?config=TeX-MML-AM_HTMLorMML-full&delayStartupUntil=configured",
+        "mathjax": "//cdn.mathjax.org/mathjax/2.4-latest/MathJax.js?config=TeX-MML-AM_HTMLorMML-full&delayStartupUntil=configured",
         "youtube": [
             // youtube URL does not end in ".js". We add "?noext" to the path so
             // that require.js adds the ".js" to the query component of the URL,

common/templates/mathjax_include.html

@@ -33,4 +33,4 @@
 <!-- This must appear after all mathjax-config blocks, so it is after the imports from the other templates.
      It can't be run through static.url because MathJax uses crazy url introspection to do lazy loading of
      MathJax extension libraries -->
-<script type="text/javascript" src="https://cdn.mathjax.org/mathjax/2.2-latest/MathJax.js?config=TeX-MML-AM_HTMLorMML-full"></script>
+<script type="text/javascript" src="https://cdn.mathjax.org/mathjax/2.4-latest/MathJax.js?config=TeX-MML-AM_HTMLorMML-full"></script>

lms/static/js/spec/main.js

@@ -43,7 +43,7 @@
             'jasmine.async': 'xmodule_js/common_static/js/vendor/jasmine.async',
             'draggabilly': 'xmodule_js/common_static/js/vendor/draggabilly.pkgd',
             'domReady': 'xmodule_js/common_static/js/vendor/domReady',
-            'mathjax': '//cdn.mathjax.org/mathjax/2.2-latest/MathJax.js?config=TeX-MML-AM_HTMLorMML-full&delayStartupUntil=configured',
+            'mathjax': '//cdn.mathjax.org/mathjax/2.4-latest/MathJax.js?config=TeX-MML-AM_HTMLorMML-full&delayStartupUntil=configured',
             'youtube': '//www.youtube.com/player_api?noext',
             'tender': '//api.tenderapp.com/tender_widget',
             'coffee/src/ajax_prefix': 'xmodule_js/common_static/coffee/src/ajax_prefix',