Any thoughts on this?

Background: Mac packages use java-like reverse domain identifiers for packages. You can see for yourself by running `pkgutil --pkgs`. One example: "com.apple.pkg.Safari6.0.4Mountain".

Our options are:
1. Require the user to specify the desired identifier
2. Provide a fallback option (that's what this test implies)
3. Try to infer one from other information in the project config (is this feasible?)