Added worker-id command line parameter

[TMaYaD]

Description

This change adds a --worker-id which will be used for worker to identify itself. The user is expected to make sure these are unique.

Motivation and Context

We needed to start and (safely) shutdown workers based on resource availability. In order to use disable-worker rpc call we needed the worker id. But there is no way to know the same. We can't rely on the included host name since we are using ECS to run the workers inside containers
This change allows us to set the worker-id using a known uuid and other details and use the same to disable it later.

Have you tested this? If so, how?

This is already available is a function parameter (which doesn't seem to be used anywhere). We tested it in our own setup without any issues.

[dlstadther]

@TMaYaD I've emailed Travis CI's support about our past few PR builds not going through. They seem to think it's due the fact that no one from your lexentbio org has ever logged into Travis before. Is there any way you or someone else from lexentbio (maybe @abhik) can do so and restart your PR builds? Thanks!

[TMaYaD]

@dlstadther Done. Builds are running now. But all of the PRs are failing flake8 tests. I could use some help to fix those.

[dlstadther]

Interesting... I'm inclined to ignore some of these pep8 rules in the flake8 testing as they've gotten more strict and a little excessive IMO. I'm just not yet sure how to modify .travis.yml to add exclusions to the flake8 matrix

[stale]

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