Improved process_services() and process_service() function

- Regular rpc processing, baacklog device processing and hosting_device_removed()
all call a unified process_services() function now.

- Moved hosting_device_removed() into the cfg_agent

- Improved routing_service_helper:process_service()

- Agent registration attempts increased to 60

- Additional logging for backlog processing

Change-Id: Ied3908c604568ca49cdd7322c28207d4b65d2586