Update firebase-admin dependency to public package (#165)

Author: laurenzlong

integration_test/functions/package.json

@@ -8,7 +8,7 @@
     "@google-cloud/pubsub": "^0.6.0",
     "@types/lodash": "^4.14.41",
     "firebase": ">3.6.9",
-    "firebase-admin": "https://storage.googleapis.com/functions-dev-preview/firebase-admin-5.4.0-rc5.tgz",
+    "firebase-admin": ">=5.4.0",
     "firebase-functions": "./firebase-functions.tgz",
     "lodash": "^4.17.2"
   },

package.json

@@ -38,7 +38,7 @@
     "@types/sinon": "^1.16.29",
     "chai": "^3.5.0",
     "chai-as-promised": "^5.2.0",
-    "firebase-admin": "https://storage.googleapis.com/functions-dev-preview/firebase-admin-5.4.0-rc5.tgz",
+    "firebase-admin": "~5.4.0",
     "istanbul": "^0.4.2",
     "mocha": "^2.4.5",
     "mock-require": "^2.0.1",
@@ -48,7 +48,7 @@
     "typescript": "^2.0.3"
   },
   "peerDependencies": {
-    "firebase-admin": "https://storage.googleapis.com/functions-dev-preview/firebase-admin-5.4.0-rc5.tgz"
+    "firebase-admin": "~5.4.0"
   },
   "dependencies": {
     "@types/express": "^4.0.33",