Icons and click action in the service worker (safwanrahman#49)

* Icons and click action in the serivice worker.

* Update webpush_serviceworker.js

* README updated.

* Small debugging leftover in the service worker.

* Fixed error where multiple notifications would open the same url

releasing version 0.2.6

release 0.2.5

upgrading version

adding version

more rst fix

Making release 0.2.1

Bumping version 2.0.0