v0.5.1: added browser build with webpack ; fixed dependency

• Now using dependency https://www.npmjs.com/package/qrcode
• The toBase64() method now returns an Observable<string>.
• The dependency that was used to generate QRs was generating GIFs which was really not good quality… I now used a more standard dependency qrcode.
• There is now 2 builds possible, one for headless integration npm run build and one for browser integration npm run build.browser
• Updated examples and removed ASCII encoding.