Implemented Regional API URL in config instead of hardcoded

[sluongng]

What did you implement:

Addressed #31 and #29

How did you implement it:

• Created new class: BaseUrl following the Key class template
• BaseUrl will use BaseUrl.get() and BaseUrl was exposed and totally configurable.
• Default base url is set to https://westus.api.cognitive.microsoft.com/face/v1.0/ to avoid any disruption to existing code bases.
• Added BASE_URL config template to /cognitive_face/tests/config.sample.py
• Fixed some existing typos

How can we verify it:

I have modified the test suit appropriately.

Just run python setup.py test

Todos:

• Write tests
• Write documentation
• Fix linting errors
• Make sure code coverage hasn't dropped
• Provide verification config/commands/resources
• Change ready for review message below

Is this ready for review?: YES

Is it a breaking change?: NO

[msftclas]

@sluongng,
Thanks for your contribution.
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It will cover your contributions to all Microsoft-managed open source projects.
Thanks,
Microsoft Pull Request Bot

[msftclas]

@sluongng, thanks for signing the contribution license agreement. We will now validate the agreement and then the pull request.

Thanks, Microsoft Pull Request Bot

[huxuan]

Instead of setting/getting Region, what about making it more general to set/get BaseUrl directly?

[huxuan]

Prefer to use base_url for consistency.

[huxuan]

Hi @sluongng, really appreciate for what you have done. Just some minor suggestions wish you can consider in your pull request.

[sluongng]

I have modified my solution as requested. Feedbacks are more than welcome.

[huxuan]

Thanks for your contribution!