feature request: allow --appname to change appname before anything else

[kapouer]

This would be only allowed through cli arg, as it would not make sense in any config file.
However, changing the appname requires parsing cli args before calling rc,
at which point rc parses cli args...

[cspotcode]

rc performs default argv parsing like this:

require('minimist')(process.argv.slice(2))

So you can pretty easily do this manually yourself, then check for an appname property and pass it into rc.