Update metadata label to match Whitehall

Whitehall has been updated to simplify metadata into "From", "History"
and "Part of" groups. Organisations are in the "From" group.

Also move the conditional to wrap the whole metadata block.
Remove static immigration manual

It was just a placeholder manual to help in getting the app ready to
display both HMRC and non-HMRC manuals. Now that it's possible to
publish manuals from specialist-publisher it's no longer needed.
Merge pull request #45 from alphagov/remove-static-immigration-manual

Remove static immigration manual
Merge pull request #43 from alphagov/update-metadata-label

Update metadata label to match Whitehall
Add web_url to static manual organisation tags

The app is now expecting this to be provided as part of the Content API
response.