Taskflow 0.1.3 was released

A summary of this release:

- Bug fixes, code cleanup
- Unicode/str fix (mishandling user data)
- Zookeeper logbook backend (optional usage)
- Exception name cleanups
- Automatic zookeeper, mysql, postgres testing (optional usage)
- Tox.ini venv expansion to test more requirement variations

Change-Id: Ibd23108c93e23202a9ef5de0ec770968c51966f1
Merge "Taskflow 0.1.3 was released"