xenapi: BitTorrent seed fails to execute because popen is passed integer

[Rick Harris]

The bittorrent seeder code is passing a list of arguments to `utils.make_process` which in turn passes those to popen. The semantics of `popen` is to only accept string arguments, so this causes a failure.

The solution is to cast all of the arguments into a string before calling.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/37137

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/37137
Committed: http://github.com/openstack/nova/commit/3cc2264eea7fb5e052459a9f00a047775a5eb88f
Submitter: Jenkins
Branch: master

commit 3cc2264eea7fb5e052459a9f00a047775a5eb88f
Author: Rick Harris <email address hidden>
Date: Mon Jul 15 21:21:04 2013 +0000

    xenapi: Pass string arguments to popen

    The current BitTorrent code was passing integer arguments to `make_subprocess`
    which would in turn pass those to `popen`. This would cause a failure because
    the semantics of the underlying `execve` function is to only accept a list of
    strings.

    The solution is to cast the arguments to a string before passing them into
    `make_subrpocess`.

    Fixes bug 1201594

    Change-Id: I8372795ca032420641c449cb07bb47f9252ff4ef