tests/test_baseapi.py: test POST w/ query in body
tests/test_baseapi.py: test POST w/ query in body

When a POST request is sent with the query in the body,
instead of as a querystring, then:
- the querystring should be empty
- the body be the JSON encoded dictionary with the query and
  other specifiers
- the Content-Type should be 'application/json'

Co-authored-by: Bill Ward <c692d6a10598e0a801576fdd4ecf3c37e45bfbc4@admintome.com>

puppet-community/pypuppetdb,voxpupuli/pypuppetdb