Add contact details for councillors

[stevenjmesser]

GovEval provides a database of councillors in the UK, a paid-for product, which powers WriteToThem but there isn't an open dataset for contact details of councillors in the UK. This makes it hard for startups, indie developers and the community to create products for councillors. However, most council websites list councillors' contact details on their websites.

It'd be great to see an improvement made to the scraper to collect contact details for councillors.