[Buildbot] #3518: Add support for worker pools

[Buildbot trac]

#3518: Add support for worker pools
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Reporter:  thalin     |      Owner:
    Type:  undecided  |     Status:  new
Priority:  minor      |  Milestone:  undecided
 Version:  master     |   Keywords:  master-slave slave
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 Configuring each worker in a config file can be painful when adding many
 identical workers, such as in an Amazon or Docker environment. As an
 administrator of a private Buildbot instance, I would like to be able to
 configure a scalable group of workers with one configuration directive,
 such as:

 {{{c['workers'] = [worker.workerPool("poolname", "password", ...), ...]}}}

 and have N workers able to register using the pool name and password. Then
 in builds, I should be able to specify just the pool name and have any
 worker from that pool be able to execute those builds.

 This would allow blind scaling of workers, which is useful in environments
 such as Docker Compose, where adding new workers would become as simple
 as:

 {{{docker-compose scale worker=5}}}

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Ticket URL: <http://trac.buildbot.net/ticket/3518>
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Buildbot: build/test automation