Update Angular and spin.js

[puku0x]

Hi,

Thank you for your example.
I realized that the sample app showed an erroe like fgnass/spin.js#356 .

After spin.js v3 was released, you can change the code as following.

// [Before]
// spinner.component.ts
declare var Spinner: any;

// .angular-cli.json
"scripts": [
  "../node_modules/spin.js/spin.js"	
],

// [After]
// spinner.component.ts
import { Spinner } from 'spin.js';

// .angular-cli.json
"scripts": [],

Moreover, I updated Angular to v5 and used BehaviorSubject to simplify spinner.service.ts.
Please use my PR if you like it 😃