backport changes from master branch

This brings default values for mappings, IFALIAS support, additional
device types support, and multiple fixes.
document additional changes
sync with master branch
fix spelling errors
avoid a warning for model without type
backport enhancement from master branch
update expected results
document lastest changes
openvz: avoid duplicate VM

if libvirt is already available, we disable the openvz module.
drop invalid SNMPv3 credentials
kill spurious whitespace
refresh the changes file
prepare the 2.3.4 release
typo: fix the %params key name