TM - Improve the communication beetween gazelle, simulators and systems

- relate the teststeps to the transactionUsage
- add the posibility to the system to choose the well configuration that the simulator should use to contact the system.
- send the configuration used by webservice on the method sendMessage
- improve the nomination of TestInstance on the simulators (add the notion of session to distinct testInstance from different gazelle).
- add synchronisation beetween contextualInformation of gazelle and contextual information of simulators
- add the notion of testInstanceStatus for simulators ( add the possibility to close a testInstance on the simulator using the ws method : stopTestInstance)