Archive complete dataset

Archives a complete dataset (views, sources, mapping, and data) via the ostool archive subcommand `one`. For example to archive a dataset called *openspending-example* users run:

    ostool [ini-file] archive one openspending-example

This will create a directory called openspending-example (path can be overwritten with the `--output` parameter with a model.json file, visualisations.json files and a source directory with all sources.

csvimport can now import the archive as well (albeit one must point to the correct files. To import an archive (e.g. openspending-example from above) users can run:

    ostool [ini-file] csvimport --model model.json --visualisations visualisations.json sources/*