Remove hardcoded dependency on a process argument.

[yelgulwa]

The process argument list could be different in some case like a packaged and un-packaged Electron app. In our case, the code threw an error because this variable did not exist.

[mattallty]

Thank you for tour PR but this breaks tests as you can see.
Maybe something like this would be preferable: (to be tested)

this._bin =(process.argv && process.argv.length >= 2) ? path.basename(process.argv[1]) : '';

[yelgulwa]

Hello @mattallty, thanks for your response. But a library should contain a good class signature and some sane defaults. The actual value to be passed should be left up to the caller. It could a value from a process argument or an environment variable etc.

[mattallty]

@yelgulwa could you please fix your PR with the given code ? Would be happy to merge it.

[mattallty]

Closed but will be fixed in #75