This uses the existing api extension to implement the actual control
of the fields, but the check is based on a new dummy extension
called os-extended-networks.
Api sample tests added for new extension.
DocImpact: Adds an extension that enables extra fields for network
create. The new fields are:
mtu: int (default flag) if set, nova sets the mtu on bridge. This
allows network_device_mtu flag to be set per network.
dhcp_server: ip (default == gateway) if different from gateway, sets
nova to assume gateway is external.
enable_dhcp: bool (default true) false will disable dhcp on network.
share_address: bool (default flag) if specifed, network will have
the same dhcp ip on every host. This allows
share_dhcp_address flag to be set per network.
allowed_start: ip if specified, reserves all ips before allowed_start.
allowed_end: ip if specified, reserves all ips after allowed_end.
Partially-implements blueprint better-support-for-multiple-networks
Change-Id: I577fe5f6560be50106f345a42a826e97d5e7d64c
71fabdc8dc