fontinfo.plist import/export v4. update for PR 215

see https://github.com/metapolator/metapolator/pull/215
No, the goal of this task is to export more metadata for *every* instance. And the whole greater task is to create better ufos on export. There must be a fontinfo.plist for every exported instance, it is ok if it only contains the minimal *shared* or *shareable* information, but that minmum should definitely be managed in one central file. I'm talking about stuff like copyright or maybe covered languages etc. Keep in mind that the most instances that we are exporting are not directly the result of an import, but got changed in some way or the other. If we would only just directly re-export imported masters, the whole point of metapolator would be none.