daemon: add connectivity changed API
Issue generated from Tuleap's migration script. Originally submitted by: Stepan Salenikovich (ssalenik)
Add a way for the clients to notify the daemon that the Internet connectivity has changed. eg: if the interface has been changed, or else connectvity was lost or (re)established.
In response, the daemon should re-load the accounts if necessariry.
The goal is to be able to seamlessly reconnect all accounts without intervention from the user in various cases. Eg: laptop users changing wifi.