Refs #68 - Added flake8 to the test suite.
Refs #68 - Added flake8 to the test suite. Fixed code to be PEP8 compliant. Refactored 'make documentation' so that code's doctests are not checked by Sphinx (they are by 'make test-app').
Refs #68 - Added missing 'etc/nose-app.cfg' file.
Merge pull request #70 from novagile/68-pep8

Closes #68: Added flake8 to the test suite.