Adding link to contacts-mobil-webapp in README.

Motivation:
This quickstart no longer has a webapp, it was extracted into a separate
module in client/contact-mobil-webapp, hence the instrutions to access
the webapp are currently incorrect.
Removing js related things are no longer in this module.

- They have now been moved to ../client/contacts-mobile-webapp
initial commit of swift port of ios-push-quickstart