Bug 1107571 - Stop uploading the uploaded_files manifest, r=armenzg

If we drop the usage of manifest_url_file then we should have a way to specify what file to use to write the json file to.

In this case, we should be able to specify the path to uploaded_files.json, hence, from the outside knowing what file will contain the mapping of files. As of now, when calling this, we assume the internal filename.