Clusterdock

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* Workaround for /etc/localtime mount failing on Mac.

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* Update to work against docker-py > 3.0.0.

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* Add --port argument functionality to clusterdock start.

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* Add support for build action.
* Use Docker labels for clusterdock nodes and clusters.
* Enhance clusterdock manage action.
* Add clusterdock ps action.
* Add clusterdock cp action.

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* Add nodes to /etc/hosts during start.

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* Fix docker-py dependency to 2.7.0.