Update: restore workflow_type WorkflowExecution's attribute

+ In order to enhance and boost metrics collection,
WorkflowExecutionQuerySet will return WorkflowExecutions
which workflow_type attribute is set. New http request has
been avoided.
Bump version to 0.1.30
fix to add markerName to recordMarkerDecisionAttributes
Merge pull request #30 from hansotronic/master

record marker failes because markerName is not added to recordMarkerDecisionAttributes
Merge branch 'release/0.1.31'
Merge branch 'master' of github.com:botify-labs/python-simple-workflow

Conflicts:
	swf/__init__.py
Merge branch 'develop'
Merge pull request #27 from botify-labs/refactor/restore_workflow_type

restore workflow_type WorkflowExecution's attribute
Merge branch 'develop'
Bump version to 0.1.32
Fix actors.worker: import missing exceptions
Merge branch 'master' into develop