Kuryr doesn't create the default subnets

[Taku Fukushima]

Kuryr uses the default subnet for the CIDR defined in the config file. Kuryr assumes the CIDR for the subnet is covered in the subnetpool created in advance and it should create anew subnets with the subnetpools.

However, current Kuryr just queries the subnet with the subnetpools defined in the config file and it doesn't create new subnets. Instead, it should examine if the given CIDR for the endpoint creation can be covered by the subnetpools and create subnets if they don't exist. If they exist, it should reuse the pre-existing subnets instead.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/224567

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/224567
Committed: https://git.openstack.org/cgit/openstack/kuryr/commit/?id=28f356990beb8c28eed4b9d4da88c0915f47c1b3
Submitter: Jenkins
Branch: master

commit 28f356990beb8c28eed4b9d4da88c0915f47c1b3
Author: Taku Fukushima <email address hidden>
Date: Thu Sep 17 19:14:41 2015 +0900

    Fix Kuryr to create the default subnets and return allocated CIDRs

    Previously Kuryr queried the subnets with the names of the subnetpools
    and therefore it always concluded there was no default subnet and
    created a new one.

    This patch fixes that behaviour and makes Kurry create new default
    subnets associating them with the pre-defined subnetpools which names
    would be given in the config file if they don't exit yet. If they exist,
    Kuryr reuse them.

    This patch also fixes Kuryr to return CIDRs combining the subnet CIDRs
    with the IP addresses allocated by Neutorn's IPAM. This covers the case
    none of Address and AddressIPv6 is given in the request.

    Change-Id: If15e2509fdb28599cd5e9a0d21464bc97ea2dcb1
    Signed-off-by: Taku Fukushima <email address hidden>
    Closes-Bug: #1496284