Create bundle_manifest.py

A first stab at a tool to bundle the pkginfo and pkg files as found in a given manifest. There are two options right now: --process-optional (-o) which will also process optional_installs items, and --process-nested (-n) which will also process any included manifests and add any found managed_installs (and optional_installs if -o is set) items to the bundle.

Currently the tool simply prints all found pkgsinfo and pkgs items to the terminal.