Remove content api from manual publishing pipeline

Manuals are no longer published to content api but instead published to content store via the publishing api. This is a first step towards removing content api.

with @tommyp
Export to publishing api before rummager

We should publish content to content store before publishing to search. This is so that when something arrives in search there is no way a user can reach the page before the content is available in the content store
Merge pull request #254 from alphagov/remove-content-api

Remove content api from manual publishing