(PUP-3281) Remove latest_info methods from yum provider

This commit removes the deprecated #latest_info and #latest_info=
methods from the yum provider.

This commit is part of the Puppet 4 code removal effort.
Merge pull request #3116 from whopper/pup-3281/remove-latest_info-yum

(PUP-3281) Remove latest_info methods from yum provider