Let user trend over a timeline that they define using the slider bar.

1) determine if the subset of data can run client side or if it requires service side calculation based on a query.

2) Change trend icon color on map when we change temporal scope of TP data we are looking at. We'll need to limit how users can set their own trend analyses, i.e. we don't want people running a trend analysis using 2 years of data and saying they found a "significant" trend using our data and test.