Making salt/cloud/clouds/opennebula python3 compatible
Added some pylint disables to handle six imports

Some of the `import __future__ from absolute_import`'s were confusing
pylint on Jenkins. I checked that the version of six on Jenkins is
up-to-date-enough to actually import the modules that are now disabled,
and they all worked as of at least six 1.5.2.
Merge pull request #18039 from rallytime/some_pylint_fixes

Added some pylint disables to handle six imports
Merge pull request #17979 from nmadhok/cloud/clouds-python3-opennebula

Making salt/cloud/clouds/opennebula python3 compatible