Tidy up reconnection logic.

Jira issue: wp-1196
Make isConnected a public method

Useful for subclasses to determine connection status.

Jira issue: wp-1196
Add zone notification service.

This is a privileged service and requires initialisation with the PzpObject.

Jira issue: wp-1196
Remove notifications from sync

Notifications sync doesn't work due to the potential for more than one entity to update the same notification, resulting in endless update cycles.

Now uses a basic transactional system.

Jira issue: wp-1196
Remove unused message type.

Jira-issue: wp-1196
Merge pull request #63 from TobyEalden/wp-1196-invite-merge

Wp 1196 invite merge