added a PCMMResourceSet to manage the PCMM resources mapping 
it's a generic api could be used to map any kind of objects, the test
class PCMMResourceSetTest defines the use case of mapping flowID to a
structure PCMMIDHolder which holds flowID, gateID and transactionID
Merge pull request #11 from rhajamor/master

added a PCMMResourceSet to manage the PCMM resources mapping