Auto-tagging

Already, there is a beta implementation at https://github.com/REEEP/ckanext-climate-tagger using the [Reegle tagging API](http://api.reegle.info/)

In the beta implementation, [it only auto-tags the Title/Description metadata fields](https://github.com/REEEP/ckanext-climate-tagger/issues/2). It'd be awesome if it can also tag the datasets themselves.

We're currently using the Reegle API to auto-tag PDFs and its quite powerful.

Start by reviewing the beta implementation in ckanext-climate-tagger and its issue about tagging only Title/Description fields, then inspect how the Reegle tagging API is used for PDFs. Done should extend tagging beyond those metadata fields to the datasets themselves, though the issue does not define the dataset scope or acceptance criteria.

Written by the indexing model from the issue text.