Add example data formatted in ICASA standards

[dlebauer]

@JeffWhiteAZ has data from the Hot Cereal Cereal experiment and cotton yield trials that comply with ICASA variable naming conventions, stored in both JSON and spreadsheet format.

• add both spreadsheet and json formatted data to the Box folder (https://uofi.box.com/terraref); we can use this as a starting point for discussions of data and metadata formats.

[dlebauer]

The example ICASA data and documentation are in https://uofi.box.com/terraref-icasa