Add python-heat-agent-json-file to the heat docker agent
Add python-heat-agent-json-file to the heat docker agent

This patch adds a new hook to the docker agent to help with
add hoc json file creation for kolla_configs and puppet
config file generation.

Change-Id: Id3f779b11e23fd3122ef29b7ccbae116667d4520
Depends-On: I2b372ac2e291339e436202c9fe58a681ed6a743f

openstack/tripleo-common,openstack/tripleo-common