Implement new APis for importer

Implement new APIS defined in document

https://docs.google.com/document/d/1n1i5Ui8N_Hp4jpG5OdNB2kf4FYtVvuudpHHJaXWlj0g/edit

1. Modify existing parameters for some existing APIs like SendDeviceInfo,Setfrquence,geteventsupported.

2. SendDeviceList- This API will add all devices in the list,

3. DeleteDevice - This API will delete the device from redfish monitoring

4. DeleteDeviceList- This API will remove all devices in the list, basically it will reset Device list(may not need next API with one device should work)

5. ListSubscribedEvents- This API will return the subscribed events for a given device

6. ClearAllSubscribedEvents - This API will remove all subscribed events to the device

7. ListCurrentDevices - This API will return current list of devices being monitored through Redfish