Ignore the work directory created when running hpi:run
Changed the version of Jenkins to build aginst to 1.509.1 (Latest Stable)
Added ui-samples-plugin as an optional dependency so as to not stop the plugin working when trying to
add it to a jenkins install that doesn't have the ui-samples-plugin.
Added a jenkins.util.TimeDuration to the doBuild call as later versions of Jenkins require this