install doc: install policy.json in /etc/cloudkitty
install doc: install policy.json in /etc/cloudkitty

The api service will not start without this file.

Change-Id: Ib87cba6df83eba7f45738733b72f3d1d331bcb2a

openstack/cloudkitty,FNST-OpenStack/cloudkitty,openstack/cloudkitty,muraliselva10/cloudkitty,stackforge/cloudkitty,FNST-OpenStack/cloudkitty,muraliselva10/cloudkitty,stackforge/cloudkitty