JCLOUDS-610: reboot, suspend, and resumeNodesMatching methods gain functionality similar to that of destroyNodesMatching

This is the PR for this JIRA issue:

https://issues.apache.org/jira/browse/JCLOUDS-610

New tests have not been written as there are already the tests "testReboot" and "testSuspendResume" of class "BaseComputeServiceLiveTest" which already cover these calls. I have however refactored these testers to account for the changes made. 


Ooo...eeek. What is this "dummy" function at the end here - is that just an evil way of calling `rebootNode` on all the matching nodes in parallel? If so, please add a comment?