ported to OSX. not tested; almost definitely needs more work.

hey Mark,

rearchitected this to make it (hopefully) work cross-platform using the Automator to add a context menu entry and Cocoadialog in place of Gtk. not yet tested, but if you want to ensure I haven't broken it on Linux/Windows, that wouldn't be a bad idea... (I'll check myself later on).
OK, sorry, I didn't respond to earlier comment. The continued appending of paths is probably a bug caused by not resetting the bag_dir variable before passing it to Python's copytree; I'd rather fix that after we merge your PR if you don't mind. The reason I was confused by the reference to /tmp is that I wasn't expecting a hard-coded path in the script. The destination for the Bags is set in the 'create_bag_in' config option. Cleaning out whatever path that is pointing to is worth considering but I think that also should be a config option. Can we defer this until we merge your PR, and then open an issue?