Upgrade underscore.string.min.js.

FED-68

common/static/js/vendor/underscore.string.min.js

@@ -0,0 +1 @@
+../../../../node_modules/underscore.string/dist/underscore.string.min.js

lms/static/lms/js/require-config.js

@@ -18,12 +18,11 @@
             }
         };
         defineDependency("jQuery", "jquery");
-        defineDependency("_", "underscore");
-        if (window._ && window._.str) {
-            define("underscore.string", [], function () {return window._.str;});
-        }
-        else {
-            console.error("Expected _.str (underscore.string) to be on the window object, but not found.");
+        defineDependency("s", "underscore.string");
+        // Underscore.string no longer installs itself directly on "_". For compatibility with existing
+        // code, add it to "_" with its previous name.
+        if (window._ && window.s) {
+            window._.str = window.s;
         }
         defineDependency("gettext", "gettext");
         defineDependency("Logger", "logger");

package.json

@@ -6,7 +6,8 @@
     "edx-pattern-library": "0.10.4",
     "requirejs": "~2.1.22",
     "uglify-js": "2.4.24",
-    "underscore": "~1.8.3"
+    "underscore": "~1.8.3",
+    "underscore.string": "~3.3.4"
   },
   "devDependencies": {
     "jshint": "^2.7.0",