grizzly: add configdrive support for xenapi

[Tom Fifield]

If https://review.openstack.org/18370 is merged, configdrive support will be added for xenapi

This functionality is well present for kvm, so the documentation should be able to be simply updated to say that xenapi supports this, with the following note:

   (Dear documentation people, if using config drive with xenapi,
    the user should disable the agent as well with
    xenapi_disable_agent)

[Tom Fifield (fifieldt)]

Patch was merged

[Tom Fifield (fifieldt)]

This patch: https://review.openstack.org/#/c/23948/

should also be noted when fixing this bug

Make ssh key injection work with xenapi agent

If there's 'key_data' on an instance, and instance is not Windows, use
file injection to inject /root/.ssh/authorized_keys. If a user
specifies their own /root/.ssh/authorized_keys via 'injected files',
that will take precedence.

Note: Images for Xen that use nova-agent will need to have /root/.ssh
pre-created with modes 0700 on those directories.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/35735

[Tom Fifield (fifieldt)]

https://review.openstack.org/35735

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/35735
Committed: http://github.com/openstack/openstack-manuals/commit/c9c1a593693620f0810bcbbf435a14a8346025a1
Submitter: Jenkins
Branch: master

commit c9c1a593693620f0810bcbbf435a14a8346025a1
Author: Tom Fifield <email address hidden>
Date: Fri Jul 5 14:22:32 2013 +1000

    Add note about config drive, backing storage

    From Grizzly, config drive is now supported well in Xen.

    However, when using it, it is important to adjust the
     xenapi_disable_agent option, which this patch adds a note
    about.

    patchset2 adds a new config example snippet for backing storage

    patchset3 addresses Diane's comments

    patchset4 fixes syntax

    fixes bug 1095506
    fixes bug 1085404

    Change-Id: Ica515d3d2613d6b850bf7693715cc59dff73c5b4

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/grizzly
Review: https://review.openstack.org/36927

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/36927
Committed: http://github.com/openstack/openstack-manuals/commit/bde138eeea755581557cbc09c26508e8a2c1730c
Submitter: Jenkins
Branch: stable/grizzly

commit bde138eeea755581557cbc09c26508e8a2c1730c
Author: Tom Fifield <email address hidden>
Date: Fri Jul 5 14:22:32 2013 +1000

    Add note about config drive, backing storage

    From Grizzly, config drive is now supported well in Xen.

    However, when using it, it is important to adjust the
     xenapi_disable_agent option, which this patch adds a note
    about.

    patchset2 adds a new config example snippet for backing storage

    patchset3 addresses Diane's comments

    patchset4 fixes syntax

    fixes bug 1095506
    fixes bug 1085404

    Cherry-picked from https://review.openstack.org/35735

    Change-Id: Ica515d3d2613d6b850bf7693715cc59dff73c5b4