BACnet discovery service

[zero88]

• [x] Provide BACnet REST API endpoints to
  • [x] Discover available networks
  • [x] Get network detail
  • [x] Discover available devices by network
  • [x] Discover detail device by device id and network code
  • [x] Discover available objects by device and network
  • [x] Discover detail object by device id and network code
• [x] Provide explicit and clear BACnet data model to express in API and integrate with edge - data point
  • [x] Network model
  • [x] Device model
  • [x] Object model
• [x] Provide cache mechanism to re-discover if cache has timeout
  • [x] Cache network
  • [x] Cache device
• [x] Provide network validation in case of network down or obsolete due to change network interface name, MAC address. etc

[zero88]

Sub of #192