Add recent additions option

[benkeen]

One thing I'd really liked to see for the curated list is a list of recent additions. Right now the list keeps growing but there's no way to find out which species were recently added:
https://bcleps.weebly.com/curated-species.html

Suggestion:

• Group the component into tabs: Curated List | Recent Additions
• have the recent additions be optional. If not defined, the tabs don't show up. This would allow people using the tool to omit the tab after initially porting in the data (since everything is recent in that case)
• Be able to configure the number of items appearing in the list.