Upgrade to Uglify 2.7.0 to remediate a security issue

package.json

@@ -12,7 +12,7 @@
     "jquery.scrollto": "~2.1.2",
     "picturefill": "~3.0.2",
     "requirejs": "~2.1.22",
-    "uglify-js": "2.4.24",
+    "uglify-js": "2.7.0",
     "underscore": "~1.8.3",
     "underscore.string": "~3.3.4"
   },