Remove unused variables

o trove/backup/models.py:SWIFT_CONTAINER = CONF.backup_swift_container

  This variable was added in the following commit.

    commit ce208d6cabba227576f492e7647d9da5a89e7c25
    Author: ruiyuan-shen <ruiyuan.shen@hp.com>
    Date:   Mon Mar 18 14:07:37 2013 -0700

        Add snapshot ORM to reddwarf

  But there is no evidence that was used.

o trove/dns/rsdns/driver.py:DNS_HOSTNAME = CONF.dns_hostname

  This variable was added in the following commit.

    commit 0c34c75dc44876245709987a18ea004607fca815
    Author: Sudarshan Acharya <sudarshan.acharya@rackspace.com>
    Date:   Fri May 18 15:49:12 2012 -0500

        DNS Support for Instance IP.

  But there is no evidence that was used.

o trove/instance/models.py:SERVER_INVALID_ACTION_STATUSES
   = ["BUILD", "REBOOT", "REBUILD", "RESIZE"]

  This variable was removed in the following commit.

    commit 54a4ada785fd90af5134e7f38360938e0b435696
    Author: Ed Cranford <ed.cranford@rackspace.com>
    Date:   Thu Jul 12 15:01:01 2012 -0500

        Delete can now delete errored instances.

o trove/instance/models.py:VALID_ACTION_STATUSES = ["ACTIVE"]

  This variable was removed in the following commit.

    commit 9ccef6fea42454bb22c0d67bd4d2a0765f13d370
    Author: Tim Simpson <tim.simpson@rackspace.com>
    Date:   Wed Jun 27 11:12:28 2012 -0500

        Allowing resizes to be performed when MySQL is down.

Closes-Bug: #1286990
Change-Id: I79f5bb124f2702317d8d337c969c9ff8ea69a769
Merge "Remove unused variables"