Add ability to create different launch profiles

[Kaidero]

it would be cool to be able to define many custom app groups and launch them by name.
maybe with opener <profile_name> or something.

[JonathanWThom]

@Kaidero I added this here! 15f7bc2

The config object will look like this now:

{
    "default": [
        "Google Chrome",
        "Slack",
        "Calendar",
        "Notes",
        "Postico"
    ],
    "weekend": [
        "Spotify",
        "News"
    ]
}

And then you can run opener -g weekend to open the weekend group. If you leave out the -g flag, it'll just use your default list.

Thanks for the great suggestion!