Extend existing integration test with tests for idling / un-idling

[hferentschik]

siegeJenkins.sh so far only tested proxying to running Jenkins instances. The problem until recently was that there was no easy way to prior to testing, manually idle a given Jenkins instance. It would immediately restart. With the latest version of Idler this problem is fixed. Now the test harness can be extended.

The idea is to idle the Jenkins instance and then hit the proxy. The Jenkins instance should come up and the request should be forwarded.