Customise Slider to include variable Ranges

[afolarin]

• The slider in REDCap by default only allows values of 0-100 with labels of whatever you want, but the values are 0-100. This is an unnecessarily opinionated way of using the slider. It would be good to have sliders with arbitrary values. Suggestion: add the values to the field annotation in REDCap and ignore the values provided in the text

• Additionally, the utilities/index.js parser doesn't correctly parse sliders. While aRMT app supports sliders, the definitions for these were manually crafted and not parsed from REDCap.

• another refactor (perhaps we should provide the field annotations as JSON rather than text, this would be more flexible and easier to parse?

While we currently support a limited functionality replacement for the slider (i.e. the horizontal radio-button range type) see related: #15 (and #16)