(PDB-1012) WIP Make spec tests use correct Puppet version

This patch parameterizes the branch of puppet our Gemfile installs so that we
can use specific puppet versions in our spec tests.
(maint) This fixes some broken links in our commands documentation.
Fix typo in the fact-contents endpoint docs
Merge pull request #1146 from wkalt/ticket/stable/pdb-1012-unit-tests-on-master

(PDB-1012) Make spec tests use correct Puppet version
Merge pull request #1151 from wkalt/maint/fix-command-doc-links

(maint) This fixes some broken links in our commands documentation.
(docs) JVM not Java

Switch the word 'java' here for 'jvm' since we are talking about the VM
not the language in this case.
(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...
Merge branch 'stable'

* stable:
  (PDB-995) retire to_pson_data_hash in spec tests to conform to latest puppet
  (docs) JVM not Java
  Fix typo in the fact-contents endpoint docs
  (maint) This fixes some broken links in our commands documentation.
  (PDB-1012) WIP Make spec tests use correct Puppet version