Allow transfer names to begin with a dash

[helenst]

This fixes https://github.com/JiscRDSS/rdss-archivematica/issues/98

When the transfer name begins with a dash and is passed as a positional argument, argparse.ArgumentParser tries to treat it as an argument name rather than a value

This is not a problem for:

• scripts that just use argv to process the arguments
• scripts that use named arguments with an equals (e.g. ./myScript.py --name="-mysip")

However, it is a problem for:

• scripts that use ArgumentParser and named arguments without an equals (e.g. ./myScript --name "-mysip")
• scripts that use ArgumentParser and positional arguments

I've run database queries to identify the commands that needed changing, and also successfully run a test transfer beginning with a dash.

[sevein]

@helenst I think you need this flake8 change we made in vanilla AM: https://github.com/artefactual/archivematica/pull/768.