- Convert to singlespec

- update to version 1.6.0
- Improving cover and docs testenv
- Fix jitter strategies
- Begin adding our own thread pool executor
- Remove 'smart' idleness check
- Avoid tox_install.sh for constraints support
- Improve get optimal count of max_worker for pool
- Update reno for stable/ocata
- Fix time related check in rejection test
- Eliminate unneccessary patching in GreenFuture
- Add what the watcher watches to the watcher as a property
- Remove discover from test-requirements
- Typo fix: arbitary => arbitrary
- Add Constraints support
- Add reno for release notes management
- Show team and repo badges on README
- Don't include openstack/common in flake8 exclude list
- Introducing NeverAgain functionality for periodics
- Add re-raising SystemExit exception
- Add Python 3.5 classifier and venv
- turn on warning-is-error in doc build
- Switch from oslosphinx to openstackdocstheme
- Update .gitignore
- Do not check spacing if periodic disabled
- Fix 'on_failure' param not be used
- replace _callables by _works
- The python 3.4 support is removed
- rearrange existing documentation to fit the new standard layout