Simple-workflow

- 4cfa1e7 Fix models.history.builder: create better timestamp
- 4f57766 Update format: log warning message when truncating an error

- 39ca2ef Fix querysets.workflow.WorkflowExecutionQuerySet.filter arguments 44

- e6d9b4d Fix swf.querysets.WorkflowExecutionQuerySet: make domain and kwargs consistent

- 88c16be Add tests for format module
- 8befc18 Update actors.worker: wrap reason and details when task fails
- 28fea7a Add format module: wrap arguments and result
- 640ece0 Update constants: add maximum values

- 4f1be64 Update settings: compatibility with python3

- 368155e Update models.history.builder: fix History.add_activity_task_schedule_failed()