Bump up taskflow to its newest version

Taskflow 0.4 was just released so update the bounds
to be the version that is most useful for the juno
release.

Release notes @

https://etherpad.openstack.org/p/TaskFlow-0.4

Change-Id: Ib261d3d3defdb0fa396b0cef16b322bcce00c64d
Merge "Bump up taskflow to its newest version"
Update to latest oslo.vmware

* Fix seek and tell in BlockingQueue
* Add DuplicateName exception
* Add ‘details’ property to VMwareDriverException
* Enable oslo.i18n for oslo.vmware
* Add API to enable calling module to register an exception
* Imported Translations from Transifex
* Add docs target and generate api docs
* Updated from global requirements
* Work toward Python 3.4 support and testing
* warn against sorting requirements
* Add exception for TaskInProgress
* Updated from global requirements
* Refactoring to reduce noise in log files
* Imported Translations from Transifex
* Add missing session parameter to get_summary
* Updated from global requirements
* Switch off caching to prevent cache poisoning by local attacker
* Support for copying streamOptimized disk to file
* Add support for the DatastoreURL object
* Add methods to the Datastore objects
* Imported Translations from Transifex
* Add Pylint testenv environment

Change-Id: I3ac9ef2371c3d210f58f494a7b4f0c860f0d1dd7