Bug 855947 - [Contacts] Refactor the update webcontacts/contact Web Activity in Contacts App.

The pull request depends on this pull request: https://github.com/mozilla-b2g/gaia/pull/8869
Please refer to that.

The changed files:
+ update.js
+ update.html
+ manifest.webapp

Create a new page for handling the "update webcontacts/contact" Web Activity.

The time to load for launching the update Web Activity was more short. It's about 500ms.
Loose coupling.

http://bugzil.la/855947