Revert "Merge pull request #130 from jhoblitt/has_element"

This reverts commit f7a1818, reversing
changes made to 36a7b29.

I'm reverting this change because of concerns raised by Peter Meier that
it duplicates the "in" operator in the DSL.  The "in" operator is new
information that I did not posses when I made the decision to merge.
Because of this new information I'm un-merging and continuing the
discussion in the comments of
https://projects.puppetlabs.com/issues/19272

Reference: GH-130

Author: Jeff McCune