Cedar-backup3

* Fix issues discovered with peer test changes when backporting to CedarBackup2.

* Add options in util/test.py to get better output from unit tests.
* Update Python virtualenv setup to work with Python 3.5 and recent pip.
* Make various adjustments to remote peer tests, to make them safer and more robust.
* Fix problems discovered with the awscli version in Debian stretch.

* Fix typo in cback.1, noticed by Debian's Lintian checks.
* Fix logging errors with odd paths in tools/amazons3.py when ascii encoding is set.

* Fix bug in the file encoding checks for the amazons3sync tool.

* Fix or disable a variety of new warnings and suggestions from pylint.

* Improvements based on testing in the Debian continuous integration environment.
- Make the logging setup process obey the --stack command-line option
- Fix logging setup to always create the log file with the proper specified mode
- Fix PurgeItemList.removeYoungFiles() so ageInWholeDays can never be negative
- Make filesystemtests more portable, with maximum file path always <= 255 bytes