Using Docker volumes for persistent data in the bifrost container is
necessary for upgrading the bifrost services.

This change adds the following volumes:

* bifrost_httpboot
* bifrost_ironic
* bifrost_mariadb
* bifrost_rabbitmq
* bifrost_tftpboot

Ironic creates hardlinks between the TFTP master image store and the
HTTP root path when iPXE is enabled. With different Docker volumes
used for these locations we run into
https://bugs.launchpad.net/ironic/+bug/1507894 during deployment. If
we use a directory under /httpboot to store the master images this
issue is avoided.

Change-Id: I8653268d3598e7a59d2eb45c8750d45b6fc9e35f
Partially-implements: blueprint bifrost-upgrade