(maint) acceptance rake test should not assume CentOS
(maint) acceptance rake test should not assume CentOS

The acceptance rake test was prepending beaker-hostgenerator's
mapped name with a centos image. This is not desired now that we
have adjusted to use new names for the images. Allow it to just
use the name that is mapped.

ThoughtCrhyme/puppetlabs-chocolatey,ThoughtCrhyme/puppetlabs-chocolatey