In anticipation of puppet 4, start trying to deal with puppet 4 things
that can be helpfully predicted by puppet lint plugins. Also fix lint
errors caught by the puppet-lint-absolute_classname-check and
puppet-lint-empty_string-check as well as arrow alignment errors now
caught by the bundle-installed puppet-lint gem.
The $description parameter was changed from defaulting to empty string
to defaulting to undef. The yumrepo resource behaves the same either
way.
Change-Id: If5a649068f73218a98372846ba38d2c25820c78a