Test Runner Refactor + Simultaneous Test Run Support - supported by all "run types" (hosted, sauce, etc)

Refactored the test Runner system to be modular/plugin oriented and added in functionality to launch simultaneous testRunner instances.  Tested with saucelabs, chromeOnly, local selenium, and hosted selenium grid configurations successfully.

My goal is to allow for single-file selenium grid configurations as referenced in issue #111 and to create a modular basis for more test runner types and functionality in the future.