Initial experimental support for generators in execution modules

This is the first work on getting #7046 going
State module docstring
Change to header

Apparently a header is required to have it included in the "Full list of builtin state modules".
Fix `TypeError` on `GeneratorType` instance checking.
Allow for a stepped Jenkins execution.
Use the `__dict__` attribute.
Need a peek at the environment for debugging purposes.
Separate output
Some more env printing
Fix script
More explicit environment variable names. Detect Jenkins environment.
Get the correct environment variable name.
Random part of VM name from build number if available.
added defaults to keystone module
Better VM name. Zero left padding build numbers.
Add release notes for 0.16.4
Merge branch 'release_notes' into develop
Merge pull request #7094 from holmboe/apt-state-docstring

Apt state docstring
Sleep a little before running the test suite remotely.
Merge branch 'develop' of github.com:saltstack/salt into develop