Fix URI vendor module to be referenced via a relative URL.

cms/templates/base.html

@@ -77,7 +77,7 @@
             "utility": "js/src/utility",
             "accessibility": "js/src/accessibility_tools",
             "draggabilly": "js/vendor/draggabilly.pkgd",
-            "URI": "/js/vendor/URI.min",
+            "URI": "js/vendor/URI.min",
 
             // externally hosted files
             "tender": "//edxedge.tenderapp.com/tender_widget",