replace configure_libvirt.py with python code.

The port is to behave as similar as possible to the old
sh code. python should allow easier testing (tests added)
and better overall readability.

A testing matrix [1] documents my tests of this feature.

The new code uses temp files and replace instead of line by line
editing for durability.

removeConf verb has been added and used in the spec file.

known behavior changes.
0.)order of configuration values added to config files has
changed. This does not seem to cause any issues.

1.)isConfigured() now also tests libvirt's
logrotate file for vdsm configuration section.

2.)configuration version is now added to /etc/logrotate.d/libvirt
like all the other files. (used to be '## beginning of ...' with
out version). this will allow versioning of this file.
No errors in removing old configuration.

3.)removeConf (now a verb and not done in vdsm.spec.in)
now calls ovirt_store_config when running on ovirt node.
(I guess before after removing vdsm rpms and restart
the vdsm configuration would re appear)

4.) log_filters inside libvirtd.conf used to be:
"3:virobject 3:virfile 2:virnetlink      3:cgroup..."
That was due to the following sh line:
set_if_default "${lconf}" log_filters "\"3:virobject 3:virfile 2:virnetlink \
    3:cgroup 3:event 3:json 1:libvirt 1:util 1:qemu\""
now it is
"3:virobject 3:virfile 2:virnetlink 3:cgroup..."
both work fine.
[1] http://www.ovirt.org/Configure_libvirt_testing_matrix

Change-Id: I74bfe05bb4b5f5d09021f21b324f9b7d5d0fdaab
Signed-off-by: Mooli Tayer <mtayer@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/27298
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>