-fix up some TDM DUM test cases 
 -allow optional 100's in TestSipEndpoint PRACK tests
-added two new PRACK test cases:
 testUASPrack2ndOfferInNoAnswerReliableWaitingPrack
 testUASPrack2ndOfferInOfferReliableProvidedAnswer

git-svn-id: https://svn.resiprocate.org/rep/resiprocate/branches/b-uasprack-20130904@10660 ddefafc4-47db-0310-ae44-fa13212b10f2