Based on the work by @kindly on https://github.com/kindly/ckan_pycsw_import,
adds a command to the extension that allows to export easily the spatial
datasets to pycsw. This will only work for harvested ISO datasets for the time
being.

The command can be run both via paster (in the context of a CKAN install) or
independently (eg a separate server), as it uses the API to get the datasets.

TODO docs