Need to add a new task_state between 'SCHEDULING' & 'BLOCK_DEVICE_MAPPING'

[wingwj]

Now there's a 'None' task_state between 'SCHEDULING' & 'BLOCK_DEVICE_MAPPING'.

So if compute node is rebooted after that procession, all building VMs on it will always stay in 'None' task_state.
And it's useless and not convenient for locating problems.

Therefore, we need to add one new task_state(like 'STARTING_BUILD') for that period.

This new task_state also needs to be added in the Doc.
I found two related contents in the website:
- http://docs.openstack.org/developer/nova/devref/vmstates.html
- https://wiki.openstack.org/wiki/VMState

The related discussion could be found here:
http://lists.openstack.org/pipermail/openstack-dev/2014-June/038638.html

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/103287

[Sean Dague (sdague)]

Upstream patch is in WIP, so I don't consider that in progress.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean Dague (<email address hidden>) on branch: master
Review: https://review.openstack.org/103287
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[Kun Huang (academicgareth)]

Talked with wj, I would help him push this improvement

[Markus Zoeller (markus_z) (mzoeller)]

This is an automated cleanup. This bug report has been closed because it
is older than 18 months and there is no open code change to fix this.
After this time it is unlikely that the circumstances which lead to
the observed issue can be reproduced.

If you can reproduce the bug, please:
* reopen the bug report (set to status "New")
* AND add the detailed steps to reproduce the issue (if applicable)
* AND leave a comment "CONFIRMED FOR: <RELEASE_NAME>"
  Only still supported release names are valid (LIBERTY, MITAKA, OCATA, NEWTON).
  Valid example: CONFIRMED FOR: LIBERTY