Add autoreject_file support to minion authentication

This commit adds support for a file similar to autosign_file, which can
be used to automatically reject minions which match the expressions
inside it.
prepend root_dir to autoreject_file
Add autoreject_file to master config template
Add autoreject_file to master config file documentation

Included a versionadded directive to note when this was added, to reduce
confusion.
Minor spelling change.
Optimize imports.
Auth system unit testing framework.

* Setup testing classes and imports
* Test load_name()
Adding execution and state modules for xmpp
We don't need to pull the roster
Add note about refresh option to pkg state.
Closes #9420.
Merge pull request #9422 from techhat/xmpp

Adding execution and state modules for xmpp
White-space related lint fixes.
Include the coding header
PyLint wrongly reports an error about calling `super()`
Merge pull request #9423 from cachedout/pkg-doc-fix

Add note about refresh option to pkg state.
Disabled the wrong Pylint code
Add a fake class to avoid problems when `sleekxmpp` is not available.
Merge pull request #9427 from s0undt3ch/develop

Add a fake class to avoid problems when `sleekxmpp` is not available
clean up in the pkg state.
Added date to release notes for recent salt versions

These dates were pulled out of the Git commit for the tag (with a Vim
macro). I didn't go back before we started tagging releases with
annotated tags since that would take some mailing list archaeology. Also
there might be a couple instances where the tag came plus or minus a day
or two from the announcement.

Closes #9426