KAZOO-1620: add is_json_object/2 to check sub-key value
KAZOO-1620: check that the value is an object before checking properties
KAZOO-1620: updated curl commands for port requests
KAZOO-1620: add bulk response headers to cb_context
KAZOO-1622: convert crossbar_doc to use cb_context accessors more
KAZOO-1622: move naming of file downloads to util module
KAZOO-1622: file uploads handled better
KAZOO-1622: look for filename attribute on request, otherwise generate name