libvirt: remove py26 compat code in "get_console_output"
libvirt: remove py26 compat code in "get_console_output"

The "get_console_output" interface had code for python2.6 compatibility.
As we need at least python2.7, we can drop that code, which makes the
method (a little) easier to read.
The unit tests don't need any change, as the expected result is the same.

Change-Id: Ic3c22b96937a836dbc50b7ce3b2ba1a864450180

rajalokan/nova,gooddata/openstack-nova,mahak/nova,gooddata/openstack-nova,gooddata/openstack-nova,rajalokan/nova,klmitch/nova,rajalokan/nova,klmitch/nova,rahulunair/nova,klmitch/nova,vmturbo/nova,mikalstill/nova,hanlind/nova,jianghuaw/nova,mahak/nova,hanlind/nova,Juniper/nova,phenoxim/nova,gooddata/openstack-nova,vmturbo/nova,Juniper/nova,mikalstill/nova,Juniper/nova,openstack/nova,openstack/nova,Juniper/nova,jianghuaw/nova,rahulunair/nova,mahak/nova,rahulunair/nova,jianghuaw/nova,klmitch/nova,hanlind/nova,phenoxim/nova,openstack/nova,mikalstill/nova,jianghuaw/nova,vmturbo/nova,vmturbo/nova,rajalokan/nova