Add Web Notifications API

RPC bindings and node side JavaScript

Jira-issue: WP-553
Change all api services to use new webinos-rpc module.

Since all services need to implement RPCWebinosService they now depend on
webinos-rpc module where that interface is defined.

Jira-issue: WP-258
Change WebNotification API feature string to match specification

The WebNotifications API needs to have feature string
'http://webinos.org/api/notifications' in order to be compliant
with our specifications.

Jira issue: WP-784
WebNotification move to a newer repository