Coverage at 99% according to coverage.py
* `compare_perf_tests.py` now always outputs the same format to stdout as is written to `--output` file
* Added integration test for the main() function
* Added tests for console output (and suppressed it leaking during testing)
* Fixed file name in test’s file header
compare_perf_test.py is now covered with unit tests and public methods are documented in the implementation.
Minor refactoring to better conform to Python conventions:
* classes declared in new style
* proper private method prefix of single underscore
* replacing map with list comprehension where it was clearer
Unit test are executed as part of validation-test.
.gitignore was modified to ignore .coverage and htmlcov artifacts generated by the coverage.py package
