0.2.1

Fix separator options parser - OptionParser defaults to boolean if no string precedes the argument.
Clarify that the TOKEN_URL host is used as filename for write, not the URL as a whole.
Add audience optional argument authorisation request.
Cleaner error output when parsing arguments.

0.2.0

Added host argument to customise the callback hostname to enable running this on a remote machine.
Added write flag to write the token contents into a JSON file in the current working directory where this tool is invoked.