UI for API users

www.agileplannerapp.com/boards/173808/cards/4993

Corrected integration tests, `page.has_selector?` was provided incorrect arguments.

Feedback from PO review:
1. @alext suggested we show a truncated access token so that it's easier to match it with configuration.
2. Restrict the user status text displayed on API user edit page to sensible values for API users.
3. Fix links on user index page to go to the correct edit page.
4. fix for multiple 'signin' permissions being created.