Editor API endpoint and controller so webhook/projects repo can speak to one another

[chrisruk]

Create Editor API endpoint and controller so webhook/projects repo can speak to one another (in Rails) - we might want to set up SMEE at this point

See digital-editor#63 for further information

[create-issue-branch]

Branch issues/115-Editor_API_endpoint_and_controller_so_webhook/projects_repo_can_speak_to_one_another created!