extension: json datastore

https://github.com/joetsoi/ckanext-jsondatastore

This is an extension that I've wanted to work on for a long time. I haven't done more than test that it's possible. I'd like to replace the datastore, because I hate it (that's a lie, hate is a strong word), with a json based datastore using a postgres jsonb field for storage. This allows more flexibility and we don't need to care so much about data types when importing.

csv files are generally a bit rubbish when detecting field types, numeric, datetime and it often gets it wrong. Basically because csv files are 'weakly typed' as it were and a database is 'strongly type' (by whcih I mean you have to specify exact data types). With a json datastore, we don't need to care and we can leave the concerns of datatype to the user of the datastore because our datatypes will be a more flexible json format

This also would full fill the wishes of people who want a hipster nosql datastore, because jsonb is even more hipster.

(bonus wish, not to use raw sql, but to provide an equivalent api that allows the functionality of any sql query people wish. Mainly because raw sql keeps me awake at night.