Docker-py

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* **This version introduces breaking changes!**
* Switched to server side build system
* Removed the BuilderClient
* Added support for contextual builds
* Added support for remote URL builds
* Added python 3 support
* Added bind mounts support
* Added API version support
* Fixed a bug where `Client.port` would fail if provided with a port of type number
* Fixed a bug where `Client._post_json` wouldn't set the Content-Type header to `application/json`

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* Added support for custom loggers in `Client.build`
* Added `Client.attach` command
* Added support for `ADD` command in builder
* Fixed a bug in `Client.logs`
* Improved unit tests

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* Added tag support for the builder
* Use `shlex` to parse plain string commands when creating a container
* Fixed several bugs in the builder
* Fixed the `quiet` option in `Client.images`
* Unit tests

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* Improved error reporting

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* Fixed a bug in `Client.tag`
* Fixed a bug where generated images would be removed after a successful build

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* Implemented first version of the builder client