feat(rc): Implement rc0 API

Author: davideast

package.json

@@ -1,6 +1,6 @@
 {
   "name": "angularfire2",
-  "version": "4.0.0-rc1",
+  "version": "4.0.0-rc0",
   "description": "",
   "main": "bundles/angularfire2.umd.js",
   "module": "index.js",

src/auth/auth.module.ts

@@ -1,6 +1,6 @@
 import { NgModule, NgZone } from '@angular/core';
 import * as firebase from 'firebase/app';
-import 'firebase/database';
+import 'firebase/auth';
 import { FirebaseApp } from '../app/index';
 import { AngularFireModule } from '../angularfire2';
 import { AngularFireAuth } from './index';