Simpleflow

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- Don't send exception up if raises_on_failure is false (213)
- Fix UnicodeDecodeError on windows machine (211)
- Try to use less memory (209)
- Standalone mode: use created task list for children activities (207)

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- Fix workers not stopping in case they start during a shutdown (205)
- Add support for SWF signals (188)
- Improvements on canvas.Group (204)

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- Implement metrology on SWF and local workflows (186)

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- Try..except pass for NoSuchProcess (182)

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- Add optional canvas (193)
- Reorganize tests/ directory (198)
- Relax DeciderPoller task list check (201)
- Implement priorities on SWF tasks (199)

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- Fix SWF executor not accepting ActivityTask's in submit() method (196)