Fix 'Bad SOAP Packet returned. Sometimes a retry will solve this error.' error with kerberos auth

When using kerberos auth against server 2012, if I had a script that didn't provide any output for >= 15s, I would start seeing 'Bad SOAP Packet returned. Sometimes a retry will solve this error.' errors.   Digging into it, I found Windows was giving a 401 response and winrm wasn't looking for it, so it tried to parse the empty body as XML which failed.

This patch will catch the 401 and re-initialize kerberos auth.  It also checks to make sure it doesn't end up in a endless reauth loop.

This pull also contains minor changes I had to make testing work properly.  These are the same test changes I added for #56.