Change the num_engine_workers to greater than current 1

[Angus Salkeld]

Now that we have decouple-nested merged, it makes sense to enable more workers.

Also taking this into account (http://httpd.apache.org/docs/current/mod/prefork.html)
one of the limiting factors can be memory. Given that our gate machines might be
memory constrained, let's just do 2 in the gate.

[Steve Baker (steve-stevebaker)]

but to be clear, what we set our config default should be appropriate for production, so 4 might make a good default.

[Angus Salkeld (asalkeld)]

Review: https://review.openstack.org/#/c/165396/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/165396
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=8c5b3589e2a3ff11a25f5bf2cf9ad8cff7c8dbdf
Submitter: Jenkins
Branch: master

commit 8c5b3589e2a3ff11a25f5bf2cf9ad8cff7c8dbdf
Author: Angus Salkeld <email address hidden>
Date: Tue Mar 31 07:55:18 2015 +1000

    Change the default num_engine_workers to get_worker_count()

    Now that we have decouple-nested merged, it makes sense
    to enable more workers. oslo has a function just for this
    processutils.get_worker_count()

    Also set the number to 2 for functional tests to
    not overly consume too much memory but still test
    the multi worker path.

    Change-Id: I86d1e8bb1813ccdee959f7a0fe78867dde7d21b5
    Closes-bug: 1434339