Handle exceptions when deleting networks and ports with NVP

- if network/port doesn't exist in NVP anymore, delete from quark db
- if network/port does exist in NVP, delete from quark db and then add
  info about it to new orphaned db tables

RM6485
Merge pull request #165 from jmeridth/handle_missing_networks_in_nvp

Handle exceptions when deleting networks and ports with NVP