Add support for authorized_keys files.

Each user can have a set of authorized keys for public key authentication.
This is better to support as it lets us use different algorithms and not
just RSA. In the age of security, it's good to have variety.

I also added additional libraries to support ed25519-based public keys.

I updated the SSH libraries so any upstream bug fixes are applied, fixed
some warnings and a few other things.

src/main/java/com/ryanmichela/sshd/ConsoleCommandFactory.java

@@ -1,7 +1,8 @@
 package com.ryanmichela.sshd;
 
-import org.apache.sshd.server.Command;
-import org.apache.sshd.server.CommandFactory;
+import org.apache.sshd.server.command.Command;
+import org.apache.sshd.server.command.CommandFactory;
+import org.apache.sshd.server.channel.ChannelSession;
 import org.apache.sshd.server.Environment;
 import org.apache.sshd.server.ExitCallback;
 import org.bukkit.Bukkit;
@@ -16,7 +17,7 @@ import java.io.OutputStream;
 public class ConsoleCommandFactory implements CommandFactory {
 
     @Override
-    public Command createCommand(String command) {
+    public Command createCommand(ChannelSession cs, String command) {
         return new ConsoleCommand(command);
     }
 
@@ -50,7 +51,7 @@ public class ConsoleCommandFactory implements CommandFactory {
         }
 
         @Override
-        public void start(Environment environment) throws IOException {
+        public void start(ChannelSession cs, Environment environment) throws IOException {
             try {
                 SshdPlugin.instance.getLogger()
                         .info("[U: " + environment.getEnv().get(Environment.ENV_USER) + "] " + command);
@@ -63,8 +64,6 @@ public class ConsoleCommandFactory implements CommandFactory {
         }
 
         @Override
-        public void destroy() {
-
-        }
-    }
+        public void destroy(ChannelSession cn) {}
+	}
 }