[doc] Reuse addresses from dhcp pool when possible

[OpenStack Infra]

https://review.openstack.org/132654
commit 2c24fca5ad39c1e9e36e19f4ca95c0cb07946c4a
Author: Dima Shulyak <email address hidden>
Date: Tue Nov 4 13:12:57 2014 +0200

    Reuse addresses from dhcp pool when possible

    We can get rid from static pool, by reusing dhcp
    address, assigned to node initially.

    General procedure for assignment of ip addresses
    is not changed, but i've added one more condition
    to check if ip address is in range of admin_net.ip_range
    if it is - it will be reused when creating ip address
    if not - address will be used from pool, it will guarantee
    that patch works on upgraded environments

    Also made refactoring of old code

    DocImpact
    Closes-Bug: 1271571
    Implments: blueprint get-gid-of-splitted-fueladmin-network

    Change-Id: I1fcc4532faa6b255674b589ebd44534082e29c96

[Irina Povolotskaya (ipovolotskaya)]

Once you start writing it up, add me as a reviewer, please.

[Dima Shulyak (dshulyak)]

Lets just add it to resolved issues

[Evgeny Konstantinov (evkonstantinov)]

Feel free to reopen if valid for 7.0