Ability to set custom icons

[kreatoo]

I don't know if this belongs here, but it would be really nice if there's a way to set a custom icns to an app using this.

[hraban]

you can do this but they'll only work for the launcher / "trampoline", not for the actually launched application

[hraban]

This will become obsolete if #27 pans out. Let me know if that branch causes you any problems (input github:hraban/mac-app-util/link-contents) --if it works for people I'll merge it to master and mac-app-util will take a step back further up the "trampoline" abstraction, not getting in the way of icons etc.