chore(uglify): move to latest version of uglify that support pure annotation

move to latest version of uglify that support pure annotation

Author: danbucholtz

package.json

@@ -55,7 +55,7 @@
     "tiny-lr": "1.0.3",
     "tslint": "3.15.1",
     "tslint-eslint-rules": "1.5.0",
-    "uglify-js": "2.7.5",
+    "uglify-js": "2.8.16",
     "webpack": "2.2.1",
     "ws": "1.1.1",
     "xml2js": "^0.4.17"