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.
Add support for default values to processors.
Update PlistReader to use new input variables defaults.
Move default value processing into existing for loop.
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
Update FileFinder, URLTextSearcher, and Versioner to use new default values ability.
Add debugging output for applying default values.
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