Remove unneeded requiresSvg option.
Remove unused options from user satisfaction view
Use correct Backdrop options for user satisfaction.

Sort by "_timestamp: ascending" and provide a limit of 0. This gives
us all available data, and works against live Backdrop data on preview.

It would be better to sort by "_timestamp:descending" and use a limit
of 2, since at the moment we only require 2 data points. However, this
would require us to refactor delta.js to cope with data in a different
order, and we may soon add a sparkline for this view that uses all
available data in any case. So I think this is an acceptable fix.