In order to facilitate offline installations, provide a way to list all packages that will be installed based on the current platform

[matthewadams]

Is your feature request related to a problem? Please describe.
I'm trying to perform a completely offline installation of fog and need to apt-get install all packages required before going offline. Right now, I can't find an easy way of doing that. See forum discussion here.

Describe the solution you'd like
I'd like to invoke installfog.sh with a new proposed option --list-packages or have some other invocable means that would simply print a space-separated list of the packages that would be installed on the current platform if the installation were actually being performed. This would allow me, while preparing to go offline, to do something like sudo apt-get install -y $(.../installfog.sh --list-packages).

Describe alternatives you've considered

1. Extract the package list by reading the installfog.sh script and trying to determine the list manually.
2. Perform a vanilla trial installation on the target platform, then get the list of packages from the .fogsettings' packages entry.