Update AndroidConfig (#389)

* Add EdDSA signature for AndroidConfig.

* Initialize KeyExchange- and FileKeyProviderFactories with registered "bouncyCastle" (in fact, SpongyCastle is registered).

See #308 for discussion.

Author: eidottermihi

src/main/java/net/schmizz/sshj/AndroidConfig.java

@@ -15,6 +15,8 @@
  */
 package net.schmizz.sshj;
 
+import com.hierynomus.sshj.signature.SignatureEdDSA;
+
 import net.schmizz.sshj.common.SecurityUtils;
 import net.schmizz.sshj.signature.SignatureDSA;
 import net.schmizz.sshj.signature.SignatureRSA;
@@ -28,9 +30,18 @@ public class AndroidConfig
         SecurityUtils.registerSecurityProvider("org.spongycastle.jce.provider.BouncyCastleProvider");
     }
 
+    public AndroidConfig(){
+        super();
+        initKeyExchangeFactories(true);
+        initRandomFactory(true);
+        initFileKeyProviderFactories(true);
+    }
+
     // don't add ECDSA
     protected void initSignatureFactories() {
-        setSignatureFactories(new SignatureRSA.Factory(), new SignatureDSA.Factory());
+        setSignatureFactories(new SignatureRSA.Factory(), new SignatureDSA.Factory(),
+                // but add EdDSA
+                new SignatureEdDSA.Factory());
     }
 
     @Override