Expose the organisation web_url
Expose the organisation, not just the embassies to the partial
Pass the organistion into the embassy partial
Link through to the embassy URL page

There's only ever 1 URL for all the embassy offices, so turn the first
heading (the "main" office) into a link to the Inside Gov page.
Remove some messy whitespace
Merge pull request #394 from alphagov/find-an-embassy-link

Find an embassy link