Optimized switch cloning

Implements switch spanning for the optimized driver and adds a couple
columns to the nvp lswitch table for the clone details lookup.
Merge pull request #99 from Cerberus98/oppnet

Optimized switch cloning
Changes allow_overlapping_ips behavior.

Resolves Issue #87 by changing the overlapping IPs behavior from system wide
to within the boundaries of the subnets associated with the network.
Merge pull request #101 from Cerberus98/subnets_allowed_ips

Changes allow_overlapping_ips behavior.