Add Support for Python 2 w/t CI Improvements

In the process of adding py2 support, the following extra improvements are made:

• Dropped dependency on multiprocess and dill (the 2d transform method is not relied on for performance-critical tasks)
• Refactored tests (e.g. use ctx_factory)
• pylint linting in CI builds
• Refactored examples, flake8 and pylint checks in CI build

Closes #35 (closed), #36 (closed)