[JENKINS-27260] SPNEGO for Windows in EC2 Plugin

Fixed the Windows temp directory getting set to ""
Enabled SPNEGO authentication

JENKINS-25385 and JENKINS-4995 both have comments complaining about
infinite loops when creating Windows slaves. Because SPNEGO is
unregistered for, the httpclient throws and exception that is silently
caught and causes the infinite loop.

src/main/java/hudson/plugins/ec2/win/EC2WindowsLauncher.java

@@ -30,7 +30,7 @@ protected void launch(EC2Computer computer, PrintStream logger, Instance inst) t
 
         try {
             String initScript = computer.getNode().initScript;
-            String tmpDir = (computer.getNode().tmpDir != null ? computer.getNode().tmpDir : "C:\\Windows\\Temp\\");
+            String tmpDir = (computer.getNode().tmpDir != null && !computer.getNode().tmpDir.equals("") ? computer.getNode().tmpDir : "C:\\Windows\\Temp\\");
 
             logger.println("Creating tmp directory if it does not exist");
             connection.execute("if not exist " + tmpDir + " mkdir " + tmpDir);

src/main/java/hudson/plugins/ec2/win/winrm/WinRMClient.java

@@ -200,7 +200,7 @@ private void setupHTTPClient() {
     private DefaultHttpClient buildHTTPClient()
     {
         DefaultHttpClient httpclient = new DefaultHttpClient();
-        httpclient.getAuthSchemes().unregister(AuthPolicy.SPNEGO);
+        //httpclient.getAuthSchemes().unregister(AuthPolicy.SPNEGO);
         httpclient.setCredentialsProvider(credsProvider);
         httpclient.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 5000);
         //httpclient.setHttpRequestRetryHandler(new WinRMRetryHandler());