Enable network to be scheduled to N DHCP agents

Fixes bug 1174132

Change-Id: Iabe96fd8a98f3539eb21268fb5ef58df8dbd8782
Restore correct alias for network-gateway extension

Bug 1182682

Change-Id: I85a93e6ccac32515c7ebb2dfe41ba67cf11c9d9f
Merge "Enable network to be scheduled to N DHCP agents"
Merge "Restore correct alias for network-gateway extension"