Allow ed25519 ssh keys for leap_cli
Right now, we cannot use ed25519 keys because we use the 0.x version of "supply_drop":https://github.com/pitluga/supply_drop, which uses capistrano 2.x, which uses net-ssh in an old version that doesn't handle ed25519 keys. Unfortunatly, supply_drop development seems to have stalled, and we are left with the lasted release of
1.0.0.beta2 - September 29, 2014
We should test if this will work for us.
(from redmine: created on 2016-04-03, closed on 2016-09-07, relates #6616, duplicates #6614 (closed))