Assignment of subdomains

[seanprivett]

Give sub-domains as per our current illustrative model to data products and tables

Currently our python datahub client does not assign domains/sub-domains to tables so this will need to be added to the entity and upsert_table method of the client.

If we then add a sub-domain and domain property to the table metadata we are ingesting (data-discovery-tool) it can be replicated should we need to purge dev datahub

[MatMoore]

Subdomain model
#52

[MatMoore]

When finishing this, run the script to dump data products to YAML, so we don't have to manually assign again.

I will also script the propagation of subdomain tags from data product to asset, as it's annoying to do this manually