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.
Don't ignore config file `sock_dir` setting. Fixes #8365.

Only afterwards try the system default path.
Merge pull request #9417 from cachedout/unit-tests

Unit tests
Merge remote-tracking branch 'upstream/pr/9416' into develop
Merge pull request #9418 from cachedout/unit-tests

PEP8 fix.
Merge pull request #9419 from cachedout/unit-tests

More aggressive IPC fix.
Added note about not authenticating as root when using the PAM module

Closes #4046, refs saltstack/halite#108.
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.