Setup Facebook Messenger API ver 4.0

[shnjtk]

Fixed to be able to setup Facebook Messenger with API v4.0.

It shows following prompt at claudia create --configure-fb-bot command.
We need two additional parameters, page ID and subscribed fields.

Facebook page access token: <YOUR_FB_PAGE_ACCESS_TOKEN>
Facebook App Secret: <YOUR_FB_APP_SECRET>
Facebook page ID: <YOUR_FB_PAGE_ID>
Subscribed fields (comma separated): messages, messaging_postbacks

[shnjtk]

PR#133 was very helpful, thanks @prathmj

[simalexan]

@shnjtk Thank you for your contribution! Much appreciated
May I ask you to add / modify the corresponding test?
If needed I can help out with some insight

[shnjtk]

@simalexan Sure, will do. I'll ask you if I need some help, thanks.

[shnjtk]

@simalexan I've added the test. Would you check?

I used process.stdin.emit and setTimeout for emulating user input.
Please let me know If you know a better way.

Here is a test coverage by nyc.

[cstpalash]

Isn't merged to master?