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.
fix all pylint C0325 (superfluous-parens): Unnecessary parens after 'del' keyword
Fixed a typo I missed a while back with some spacing.
Merge pull request #9486 from gravyboat/develop

Fixed a typo I missed a while back with some spacing.
Merge pull request #9485 from hulu/superfluous-parens-del

fix all pylint C0325 (superfluous-parens) warnings
Merge pull request #9483 from terminalmage/docs

More refinement of master/minion troubleshooting docs
Merge pull request #8734 from terminalmage/autoreject_file

add an autoreject_file parameter to the master config file
Add note about upstart to resource limits documentation