AIX: Set os_version to match the output of oslevel -s#790

Merged

tas50 merged 3 commits intochef:masterfrom juliandunn:aix-os-version

Apr 4, 2016

+7-6

Commits on Apr 1, 2016

Set os_version to match the output of oslevel -s instead of just the
Julian C. Dunn
committed
Added newline to mocked shell_out per code review.
Julian C. Dunn
committed
Replace with .strip per code review
Julian C. Dunn
committed