Several flake8 errors in new xenserver code

[Matt Riedemann]

I don't know why the gate isn't catching these, but I got the latest code this morning and ran a clean tox pep8 which resulted in these failures:

http://paste.openstack.org/show/47427/

Using blame, here is at least one patch that added code which is causing one of the failures but it wasn't caught in the gate:

https://review.openstack.org/#/c/47901/

[Matt Riedemann (mriedem)]

Note that the plugins/xenserver code was enabled for flake8 testing again with this patch:

https://github.com/openstack/nova/commit/2266c044588a3b961fceeb1697753a0959c24f82

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/48086

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/48086
Committed: http://github.com/openstack/nova/commit/016e39734e1b70c1b004f1ae366c22b091463932
Submitter: Jenkins
Branch: master

commit 016e39734e1b70c1b004f1ae366c22b091463932
Author: Matt Riedemann <email address hidden>
Date: Tue Sep 24 08:28:53 2013 -0700

    Fix several flake8 issues in the plugins/xenserver code

    Due to some issues in the gate, several flake8 errors got merged
    recently. This patch fixes the most recent issues found.

    For the H304 relative import errors, we have to skip those because they
    are put into /etc/xensource/scripts which is the current working
    directory when running the plugin.

    For the H231 incompatible python 3 'except x,y' construct, we have to
    skip those because this code is written to run on python 2.4 and 'except
    x as y' does not work with python 2.4.

    Note that in cleaning up some of the H304 failures for relative imports,
    I also re-arranged the imports to follow the hacking guide of doing
    standard library packages first, then third party packages, and finally
    nova-specific packages.

    Closes-Bug: #1229753

    Change-Id: I1c2211fd6a10d43d7e65cdb4e18530397788cf2c