(PDB-995) retire to_pson_data_hash in spec tests to conform to latest puppet

This commit changes calls of to_pson_data_hash to to_data_hash so that our tests
pass on the current master branch of puppet.
Merge pull request #1153 from wkalt/ticket/stable/pdb-995-pson-retirement

(PDB-995) retire to_pson_data_hash in spec tests to conform to latest pu...