Fixes #345: introduce data-source for hosts in cluster

[eslutsky]

Please describe the change you are making

This PR fixes #345 and adds the ability to list hosts by cluster ID.

Are you the owner of the code you are sending in, or do you have permission of the owner?

Yes

The code will be published under the BSD 3 clause license. Have you read and understood this license?

Yes

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[ghost]

Looks good

[ghost]

Actually, could you add examples to the examples directory?

[ghost]

@eslutsky you merged instead of a rebase. Could you rebase please?

[eslutsky]

@eslutsky you merged instead of a rebase. Could you rebase please?

done