Display document views (#849)

* Display who has viewed a document in the header

* Add overflow, display of WHEN last viewed
Cleanup old document attributes
Add firstViewedAt, lastViewedAt to API response

* Cleanup

* Added: API documentation for views endpoints

* Include views for deleted users

app/components/Actions.js

@@ -8,6 +8,7 @@ export const Action = styled(Flex)`
   align-items: center;
   padding: 0 0 0 12px;
   font-size: 15px;
+  flex-shrink: 0;
 
   a {
     color: ${props => props.theme.text};