987 Implement conference in PolycomDevice by using phone WS for actions
Together with xumgt and xivo-solutions-doc MRs closes #987
Tested on Polycom VVX300 and VVX500
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Together with xumgt and xivo-solutions-doc MRs closes #987
Tested on Polycom VVX300 and VVX500