Create a modular function to collate wikimedia pages together

See parent tasks for rationale etc.
User story 1: as a user I can still use book creator to create pdfs of a series of wikimedia pages so that I can print them or download them for later use

User story 2: as a reading team manager, I would like a service that collates articles into a single page that can be used by any extension or platform (desktop, mobile web, apps, 3rd parties)

Currently: collections extension provides OCG with a list of pages and OCG:

• receives list
• collates it
• adds a 'table' of contents to the front
• adds attribution to the bottom
• converts to LaTeX and to pdf
• returns to the collections extension for download/save, etc.

Moving forward

New service:

• receives list
• collates it
• optional: adds a 'table' of contents to the front
• optional (need to check with legal): adds attribution to the bottom
• hands to electron

Electron

• converts to LaTeX and to pdf
  • returns to the collections extension for download/save, etc.