Add AJAXSightingsListView returning sightins in JSON
Indent JSON response of AJAXListMixin
Implement custom serialiazer for Sighting objects and use it in AJAXSightingsListView
Filter sighting by jellyfish in AJAXSightingsListView
Order sightings by date
Add basic pagination to AJAXSightingListMixin
Merge branch 'ajax_sightings' into development