gluster: Audit Log Util for gluster

Utility class for gluster related audit logs. Provides convenience
methods to create audit logs related to a gluster cluster, volume,
or server. While the AuditLogDirectory is sufficient for logging
from regular BLL commands, this class can be used for creating audit
logs from other places, e.g. GlusterManager

Change-Id: If36dcf305cd6b0ee57cff3bea126f4f6acef740f
Signed-off-by: Shireesh Anjal <sanjal@redhat.com>