ls_switch_conf.py should reference/report public VLAN membership

[sadsfae]

If we use the tool /opt/quads/quads/tools/ls_switch_conf.py on systems that are assigned an optional routable public VLAN it is unable to report the correct switchport used.

We should enhance ls_switch_conf.py to notice and report on the correct last interface switchport if a cloud is assigned a public VLAN.

# /opt/quads/quads/tools/ls_switch_conf.py --cloud cloud33
INFO - Cloud qinq: 0
INFO - Interface em1 appears to be a member of VLAN 1420
INFO - Interface em2 appears to be a member of VLAN 1421
INFO - Interface em3 appears to be a member of VLAN 1422
INFO - Interface em4 appears to be a member of VLAN 1423
WARNING - Could not determine the previous VLAN member for em5, switch 10.1.34.223, switch port et-0/0/13:2 

# /opt/quads/quads/tools/ls_switch_conf.py --cloud cloud15
INFO - Cloud qinq: 0
INFO - Interface em1 appears to be a member of VLAN 1240
INFO - Interface em2 appears to be a member of VLAN 1241
INFO - Interface em3 appears to be a member of VLAN 1242
INFO - Interface em4 appears to be a member of VLAN 1243
WARNING - Could not determine the previous VLAN member for em5, switch 10.1.34.224, switch port et-0/0/22:1 
INFO - Interface em5 appears to be a member of VLAN 0

These are both assigned to optional routable public VLANS on their last interface here:

# quads-cli --ls-vlan | egrep "cloud15|cloud33"
608: cloud33
611: cloud15