Improve integration tests

Updated the integration tests so that they work on a clean Jenkins installation. 

Also had to expose DefaultHttpClient to allow it be passed in with a configured PoolingClientConnectionManager. This was to allow setTestJob() to be do an update of the test job if one already exists. This was throwing an exception when using the existing DefaultHttpClient due to the connection not being returned so I suspect that this be a bug but I have not figured out how to prevent it. Using PoolingClientConnectionManager prevents this exception.