Merge pull request #1734 from firebase/bs-570json

Create 5.7.0.json

Releases/Manifests/5.7.0.json

@@ -0,0 +1,6 @@
+{
+  "FirebaseCore":"5.1.2",
+  "FirebaseMessaging":"3.1.1",
+  "FirebaseStorage":"3.0.1",
+  "FirebaseFirestore":"0.13.2",
+}