adding support for j_validate requests

Author: adamcin

src/main/java/org/jenkinsci/plugins/graniteclient/GraniteClientExecutor.java

@@ -63,7 +63,7 @@ public final class GraniteClientExecutor {
  private static final AsyncCompletionHandler<Boolean> LOGIN_HANDLER = new AsyncCompletionHandler<Boolean>() {
  @Override
  public Boolean onCompleted(Response response) throws Exception {
- return response.getStatusCode() == 405;
+ return response.getStatusCode() == 405 || response.getStatusCode() == 200;
  }
  };
 
@@ -125,7 +125,7 @@ private static boolean doLoginSignature(AsyncPackageManagerClient client, SSHUse
  KeyId keyId = new UserKeysFingerprintKeyId(key.getUsername());
  Signer signer = new Signer(sshkey, keyId);
  Future<Boolean> fResponse = AsyncUtil.login(client.getClient(),
- signer, client.getClient().prepareGet(client.getLoginUrl()).build(), LOGIN_HANDLER);
+ signer, client.getClient().prepareGet(client.getBaseUrl() + "?sling:authRequestLogin=Signature&j_validate=true").build(), LOGIN_HANDLER);
 
  try {
  if (client.getServiceTimeout() > 0) {