GetXml methods pt2

Added a GetXml method to the TestVerification class, and did some minor
refactoring to the GenericAttribute method in NodeConstruct.
GetXML methods pt3

Added GetXml() methods to TestCompilation, Site, TestCase and TestStep
classes.
GetXml methods pt4

Added error handling to existing GetXml methods
GetXml methods pt5

Added GetXml methods to Config and TestFrame classes.