Simplified PZH/PZH certificate exchange within the same provider.

When connecting to another personal zone hub within the same
provider, avoid having to reauthenticate.

Jira issue: WP-687
Fix unwatch and remove for appstate sync

Unwatchig a property on a sync object now removes the watch listener.
Also fix reference counting for sync object. Reflect changes in updated
tests.

Jira-issue: WP-235
Minor fix: removing debug console.log entries from the sessionHandling code

Jira issue: WP-687
Merge pull request #453 from jplyle/WP-687-Simplify-PZH-Cert-Exchange

Simplified PZH/PZH certificate exchange within the same provider.
Merge pull request #452 from aldafu/WP-235-improve-unwatch-and-remove-for-appstate-sync

Fix unwatch and remove for appstate sync
Fixed bug prevents sensors to stop

Jira issue: WP-736
Merge pull request #455 from glatorre/WP-736

Fixed bug prevents sensors to stop [WP-736]