Add credential setup command
Add credential setup command

This will add a command to keystone-manage to setup a fernet key repository for
encrypting credentials.

partially-implements bp credential-encryption

Change-Id: I97e7701bc5b8765d207cc721793643bcefa2d4e2

openstack/keystone,openstack/keystone,mahak/keystone,openstack/keystone,mahak/keystone,rajalokan/keystone,mahak/keystone,ilay09/keystone,ilay09/keystone,ilay09/keystone,rajalokan/keystone,rajalokan/keystone