Configuration and Test Updates

This MR includes a couple of primary updates:

• Addition of a workbench_dir parameter to the PyARC config, this allows for specification of a Workbench installation without assuming that the necessary Workbench executables are in the bin directory with in the PyARC repo.
• The addition of a PyARCTestClass that inherits from unittest.TestCase to handle some of the common functionality across all of the test files such as the location of current_dir and the function used to diff reference files against the outputs of the tests.

Note: Many files have had trailing whitespace removed by my editor's settings. It's probably worth turning off whitespace changes when looking at the diffs to shorten them up.