Disable accounting procacct mode

[OpenStack Infra]

https://review.openstack.org/267643
Dear bug triager. This bug was created since a commit was marked with DOCIMPACT.

commit 57911011587fbf24b9e68b2a67fc3f6d1bef967e
Author: Michael Polenchuk <email address hidden>
Date: Thu Jan 14 17:57:57 2016 +0300

    Disable accounting procacct mode

    Turn off process accounting ('no procacct' mode).
    But atop still has an ability to collect valuable stats.

    Bring in internal "custom_acct_file" option:
    * false - use atop default accounting file
    * /path_to/atop.acct - custom one
    * undef - disable accounting procacct mode

    DocImpact: 'custom_accounting_file' is system wide process
    accounting file (valid values is above).

    Change-Id: Ida00dc663dd8c6494c479de2ae2f0f7ab6014a84
    Closes-Bug: #1530167