(PDB-812) Consolidate produce-body

This patch consolidates produce-body functions for all streaming endpoints to a
new function in http/produce-body.
Merge pull request #1068 from wkalt/ticket/master/pdb-812-consolidate-produce-body

(PDB-812) Consolidate produce-body
(PDB-843) Squash puppetlabs.http and puppetdb.http

These two files are a source of confusion as we develop, and the pending
namespace change requires us to do something with them. This patch simply
squashes the functions into one library for now, and removes any reference
in other libraries. The pl-http short name is also dropped now.

Signed-off-by: Ken Barber <ken@bob.sh>
(PDB-843) Move the src files into their new places

Signed-off-by: Ken Barber <ken@bob.sh>
Fix some namespaces

Signed-off-by: Ken Barber <ken@bob.sh>