api_views.py:
- changed SampleDetail view to a Retrieve only view. no longer used to apply the panel
- added SamplePanelUpdate view as an Update only view to apply the panel

urls.py:
- added route for SamplePanelUpdate view

utils.py:
- updated to raise ValidationError if a sample's parameters are already defined, avoids overwriting the params. Maybe implement a clear params function to re-apply a different panel?