contrib/cfengine.el: add 25.1 compatibility code and clean up
Merge pull request #2015 from tzz/tzz/cfengine.el

contrib/cfengine.el: add 25.1 compatibility code and clean up
contrib/cfengine.el: Support add-log-current-defun-function
Add: Acceptance test for module protocol

Should be able to use negative class expressions with classes defined
from module protocol right away.

ref: https://dev.cfengine.com/issues/6689
Merge pull request #2017 from nickanderson/redmine/6689

Add: Acceptance test for module protocol
Merge pull request #2019 from leoliu/master

contrib/cfengine.el: Support add-log-current-defun-function