Add document as field for pitch/business canvas task

[jdrever]

• [x] db change
• [x] task:front end
• [x] task:back end
• [x] changes to points
• [x] changes to team views
• [x] changes to team page
• [x] changes to moderation queue
• [x] document translations and add to en file:
• Your team has an existing pitch document. Upload a new file below to replace it
• Upload your pitch document (use a PDF or image file, e.g. JPG or PNG)
• Pitch
• EDIT PITCH