Tweak logging behavior with --report-plist as arg

Send status updates to stderr when autopkg is invoked with --report-plist
result_report written to plist file

instead of stdout.
Update ReadMe.md
Do user home expansion on CACHE_DIR and RECIPE_REPO_DIR preferences values
Merge branch 'master' of https://github.com/autopkg/autopkg
PyLint cleanups for autopkg tool
Remove all trailing whitespace from autopkglib/__init__.py
Remove all trailing whitespace from autopkglib/*.py
Remove all trailing whitespace from autopkgserver/*.py files
Remove all trailing whitespace from Scripts/*.py files
PyLint cleanups for autopkglib/__init__.py
PyLint cleanups for autopkglib/AppDmgVersioner.py
PyLint cleanups for autopkglib/BrewCaskInfoProvider.py
PyLint cleanups for autopkglib/CodeSignatureVerifier.py
Autopkg cleanups for autopkglib/Copier.py
Autopkg cleanups for autopkglib/DmgCreator.py
PyLint cleanups for autopkglib/DmgMounter.py
PyLint cleanups for autopkglib/EndOfCheckPhase.py
PyLint cleanups for autopkglib/FileCreator.py
PyLint cleanups for autopkglib/FileFinder.py