Add code from express-unpkg repo

package.json

@@ -11,16 +11,21 @@
   "dependencies": {
     "cors": "^2.8.1",
     "countries-list": "^1.3.2",
+    "csso": "^3.1.1",
     "date-fns": "^1.28.1",
+    "debug": "^2.6.8",
+    "etag": "^1.8.0",
     "express": "^4.15.2",
-    "express-unpkg": "^2.0.1",
-    "firebase-admin": "^4.2.1",
     "gunzip-maybe": "^1.4.0",
     "http-client": "^4.3.1",
     "invariant": "^2.2.2",
     "isomorphic-fetch": "^2.2.1",
+    "lru-cache": "^4.0.2",
+    "mime": "^1.3.6",
+    "mkdirp": "^0.5.1",
     "morgan": "^1.8.1",
     "ndjson": "^1.5.0",
+    "os-tmpdir": "^1.0.2",
     "pretty-bytes": "^3",
     "prop-types": "^15.5.8",
     "raven": "^1.2.1",
@@ -29,6 +34,8 @@
     "react-motion": "^0.4.7",
     "react-router-dom": "^4.0.0",
     "redis": "^2.7.1",
+    "semver": "^5.3.0",
+    "tar-fs": "^1.15.2",
     "throng": "^4.0.0"
   },
   "devDependencies": {