Pass command line options to the test tools in the test suite

[hillairet]

Currently validatecode has no way to receive options for the tools it runs.
Something like pytest has very useful options such as --last-failed or --stepwise that users may want to use during development.

One option to handle all the various tools would be this kind of CLI:

validatecode --pytest "--last-failed"

[hillairet]

So to do this you would:

1. Use the first answer of this to add and option --pytest to the test_suite script that would pass the options --pytest "OPTIONS" to pytest.
2. Then pass all the arguments given to validatecode to test_suite.sh here