Making workspace a required parameter for --list

[venkatrag1]

With the introduction of internal_testing, the --list option was broken because it created a dependency on test_runner.json whereas in prior versions --list did not require / use workspace argument.

In this PR #17, I've tackled this by making workspace a required argument for --list to support the internal_testing flag.

I have also added an option to override the base directory where the folders tests, internal_tests and ifc files are loaded from, by default is uses the s.path.dirname(file) which is the current behavior, to take advantage of this change to provide the option of storing these files in a different path when using self-contained python executables.

Wanted to signal boost this change, as well as solicit feedback on any other ways to handle this.

[venkatrag1]

Closed as the PR has been merged