jamiaccount: redo presence design

Green indicator is not understandable for the majority of users.
This patch introduces a new approach to this status. API doesn't
change, so this is 100% backward compatible but introduces new
possibilities:

1. The status sent to the client is now 0=offline (no device found
on the DHT), 1=dht_presence (at least a device is found on the DHT),
2=connected (with a TCP + SIP channel, so ready to exchange data).
2. Publish can now be used on a Jami Account. Status is ignored,
but custom note can be added. e.g. "Lunch time!"
This status is sent via a PIDF XML status as described in RFC3863
(and already supported by SIP account) to connected peers (or for
future connections).

Several scenarios are tested in ut_presence

Change-Id: I87d987bc69e97f92a0c9f4751069e52ad69ea0fc