Update jQuery to 3.x now that IE8 isn’t supported

We’ve effectively deprecated IE8 support anyway now that we use `document.querySelector` in the loader. If we ever need to reenable IE8 support, we’ll have to downgrade to jQuery 1.x.

NB: Requires us to point ot jQuery 2.2.4 on Pjax test pages since Pjax doesn’t support jQuery 3 yet.

Author: reefdog

bower.json

@@ -28,8 +28,8 @@
     "tests"
   ],
   "dependencies": {
-    "jquery":     "~1.12.0",
-    "jQuery-ajaxTransport-XDomainRequest": "~1.0.2",
+    "jquery":     "~3.1.1",
+    "jQuery-ajaxTransport-XDomainRequest": "~1.0.4",
     "underscore": "~1.8.3"
   },
   "devDependencies": {