conductor should call validate before send_sensor_data

[Anusha]

_send_sensor_data in manager.py missed to call validate before initiating driver specific call
calling validate enables conductor to validate the driver specific information and also maintains consistency with other functions in manager.py.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/125387

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/125387
Committed: https://git.openstack.org/cgit/openstack/ironic/commit/?id=d8aec8c766444f56f741dfb6a53a1b6f1a2de69e
Submitter: Jenkins
Branch: master

commit d8aec8c766444f56f741dfb6a53a1b6f1a2de69e
Author: Sam Betts <email address hidden>
Date: Wed Oct 1 16:19:14 2014 +0100

    Add a call to management.validate(task)

    Makes sure _send_sensor_data calls the driver validate method before
    calling get_sensor_data.

    Change-Id: I859ff3d315765f463a433fe3c02cb975f98972d2
    Closes-Bug: 1375103