Merge pull request #106 from FirebasePrivate/inlined.fix-exports

I previously tried `export * as database from './providers/database'` and when that syntax didn't work I tried

```ts
import * as databaseProvider from './providers/database'
export const database = databaseProvider;
```
because `export database` didn't work. It turns out the right syntax was just `export {database}`, which isn't documented in the TS docs because it's an ES6 standard.

## Bug Explanation
In TypeScript things are either types or values. A namespace is the only thing that can be both. We weren't able to name `functions.auth.UserRecord` in the past because we weren't actually exporting the namespace!

```ts
export const auth = authProvider;
```

created a new l-value (auth) that was a narrower type than authProvider was. Effectively the namespace got downcast to a value in the export!

CC @jwngr and @davideast for FYI since this is a really cool TypeScript lesson.

Author: inlined

src/index.ts

@@ -21,17 +21,12 @@
 // SOFTWARE.
 
 // Providers:
-import * as authProvider from './providers/auth';
-import * as databaseProvider from './providers/database';
-import * as pubsubProvider from './providers/pubsub';
-import * as storageProvider from './providers/storage';
-import * as httpsProvider from './providers/https';
-
-export const auth = authProvider;
-export const database = databaseProvider;
-export const pubsub = pubsubProvider;
-export const storage = storageProvider;
-export const https = httpsProvider;
+import * as auth from './providers/auth';
+import * as database from './providers/database';
+import * as pubsub from './providers/pubsub';
+import * as storage from './providers/storage';
+import * as https from './providers/https';
+export {auth, database, pubsub, storage, https};
 
 // Exported root types:
 export * from './config';

src/providers/https.ts

@@ -22,6 +22,7 @@
 
 import { TriggerAnnotated } from '../cloud-functions';
 import {Request, Response} from 'express';
+export {Request, Response};
 
 export function onRequest(
   handler: (req: Request, resp: Response) => void