indent using 4 spaces (2/3)

As advised in I072cf8bf6748d0c910fecffdf2282bcc4656d038, code should
use 4 spaces for indentation.
This commit enforces the use of 4 spaces indentation.
In order to simplify the review process, this patch only cover the
following elements:
 - nagios3
 - network-utils
 - neutron-openvswitch
 - nova-api
 - nova-baremetal
 - nova-compute
 - nova-kvm
 - openstack-client
 - openstack-db
 - openstack-ssl

Change-Id: I489746d384c0c2c5a4f2b12444606e3bf8e3ce11
Merge "indent using 4 spaces (2/3)"