Add a "private" property on nodeinfo

This property will indicate if the instance accepts to be listed publicly (as in peers API) or not.

mentioned in commit 7029fe75

mentioned in merge request !198 (merged)

assigned to @eliotberriot

mentioned in commit 1974c17e

mentioned in commit 6608a315

closed via commit 1974c17e

closed via merge request !198 (merged)

mentioned in commit 8ee34b89