Add support for SSH ed25519 keys

This works with both host and user keys.

(cherry picked from commit 763c65b84f)

Propellor/Property/Ssh.hs

@@ -122,6 +122,7 @@ fromKeyType :: SshKeyType -> String
 fromKeyType SshRsa = "rsa"
 fromKeyType SshDsa = "dsa"
 fromKeyType SshEcdsa = "ecdsa"
+fromKeyType SshEd25519 = "ed25519"
 
 -- | Puts some host's ssh public key into the known_hosts file for a user.
 knownHost :: [Host] -> HostName -> UserName -> Property

Propellor/Types.hs

@@ -150,5 +150,5 @@ data PrivDataField
 
 type GpgKeyId = String
 
-data SshKeyType = SshRsa | SshDsa | SshEcdsa
+data SshKeyType = SshRsa | SshDsa | SshEcdsa | SshEd25519
 	deriving (Read, Show, Ord, Eq)