[types] Export app, auth, database and firestore types

lib/modules/database/DataSnapshot.js

@@ -1,15 +1,15 @@
 /**
  * @flow
- * Snapshot representation wrapper
+ * DataSnapshot representation wrapper
  */
 import { isObject, deepGet, deepExists } from './../../utils';
-import type Reference from './reference';
+import type Reference from './Reference';
 
 /**
  * @class DataSnapshot
  * @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot
  */
-export default class Snapshot {
+export default class DataSnapshot {
   ref: Reference;
   key: string;
 
@@ -50,10 +50,10 @@ export default class Snapshot {
    * @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#forEach
    * @returns {Snapshot}
    */
-  child(path: string): Snapshot {
+  child(path: string): DataSnapshot {
     const value = deepGet(this._value, path);
     const childRef = this.ref.child(path);
-    return new Snapshot(childRef, {
+    return new DataSnapshot(childRef, {
       value,
       key: childRef.key,
       exists: value !== null,

lib/modules/database/OnDisconnect.js

@@ -1,17 +1,17 @@
 /**
  * @flow
- * Disconnect representation wrapper
+ * OnDisconnect representation wrapper
  */
 import { typeOf } from '../../utils';
 import { getNativeModule } from '../../utils/native';
 import type Database from './';
-import type Reference from './reference';
+import type Reference from './Reference';
 
 /**
  * @url https://firebase.google.com/docs/reference/js/firebase.database.OnDisconnect
- * @class Disconnect
+ * @class OmDisconnect
  */
-export default class Disconnect {
+export default class OnDisconnect {
   _database: Database;
   ref: Reference;
   path: string;

lib/modules/database/index.js

@@ -4,12 +4,12 @@
  */
 import { NativeModules } from 'react-native';
 
-import Reference from './reference';
+import Reference from './Reference';
 import TransactionHandler from './transaction';
 import ModuleBase from '../../utils/ModuleBase';
 import { getNativeModule } from '../../utils/native';
 
-import type App from '../core/firebase-app';
+import type App from '../core/app';
 
 const NATIVE_EVENTS = [
   'database_transaction_event',