Spylon

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- [PR-43](https://github.com/maxpoint/spylon/pull/43) Fix broken getattr
introduced in [PR-39](https://github.com/maxpoint/spylon/pull/39) and add
better testing around the SparkConfiguration getattr/setattr
- [PR-40](https://github.com/maxpoint/spylon/pull/40) Update json spark
properties for 1.6.0, 1.6.1, 2.0.2, 2.1.0 and latest. Pull code out of
spark/launcher.py and shove it into update_spark_params.py

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- [PR-39](https://github.com/maxpoint/spylon/pull/39) Fix getattr bug

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- Daemonize the progress thread to avoid hanging the process [PR-33](https://github.com/maxpoint/spylon/pull/33)

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- Improve pip installation experience [PR-29](https://github.com/maxpoint/spylon/pull/29)

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- Bugfix release.

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- Cleanup of downloaded / extracted artifacts when using spylon.spark.yarn_launcher.