Test suite doesn't run in Windows

[JFPerkins]

Currently the tests are configured to run with --boxed which explicitly calls os.fork() and results in pytest throwing an error because fork is not supported on Windows.

Removing the --boxed flag, test_files.test_output_file_no_write failed and test_files.test_output_dir_bad_permission actually just hung indefinitely.

[JFPerkins]

Well, I fixed the indefinite hanging but 4 tests continue to fail because chmod isn't actually fully supported on Windows.

https://github.com/JFPerkins/argschema/tree/fix-windows-tests

Failing tests:

• test_outputfile_no_write
• test_mode_output_osdir
• test_access_inputfile_failed
• test_inputdir_no_access