Add monitoring of HDD errors

[OpenStack Infra]

https://review.openstack.org/355889
Dear bug triager. This bug was created since a commit was marked with DOCIMPACT.

commit 99e2863c141c39b648e30fc8bbebe1fbec87dc67
Author: Ildar Svetlov <email address hidden>
Date: Tue Aug 16 14:58:48 2016 +0300

    Add monitoring of HDD errors

    This change adds a filter plugin that monitors the kernel log messages
    for hard drive errors and reports the number of errors per second
    as 'hdd_errors_rate'. The filter is configured for all nodes,
    irrespective of their roles. An alarm is also added that triggers
    a CRITICAL alert when the metric value is greater than 0.

    DocImpact

    Change-Id: I485f5692a3e5facf0f7ea019ccdbd70683a7dd4e