Use more specific testng asserts where possible

These asserts yield more informative error messages.  Found with:

grep -rI 'assertTrue(.* =='
grep -rI 'assertTrue(.* !='
grep -rI 'assertTrue(.*\.equals('
JCLOUDS-610: Return the affected nodes from resumeNodesMatching, suspendNodesMatching and rebootNodesMatching

Methods have been refactored to match the functionality provided by destroyNodesMatching.