[Config] Improve db_manage script
[Config] Improve db_manage script

Few improvements:
- use cassandra creds from contrail config files
- better output of duplicated IP/ID allocations
- Add check and clean orphan resources (could need to be run multiple
  times, no recursive delete)
- routing instance without virtual network or logical router reference
  are considering stale and cleaned
- for SG and VN duplicate ID, only keep that ID on the resource written
  on the zk lock and remove on the other (schema will re-allocate a new
  one on startup)
- instance ip without virtual network or virtual machine interface
  reference are considering stale and cleaned
- re-create missing subnet UUID mapping with virtual network/CIDR in the
  useragent cassandra table

Closes-Bug: #1718483
Change-Id: I351aeeeaf33a422909212816ad58c4a731ab6915

nischalsheth/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,nischalsheth/contrail-controller,rombie/contrail-controller,nischalsheth/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,nischalsheth/contrail-controller,rombie/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,nischalsheth/contrail-controller,rombie/contrail-controller,nischalsheth/contrail-controller