Create Et model
Add rake task to import ETo data for fabian_garcia weather station
Add Kc model
Edit import.rake to include namespace and allow updating of csv file records
Add import:kc to import.rake
Add seed data to db:test for Et and Kc
Update @irrigation.next_irrigation to use Et * Kc for daily Et and iterate until AW = 0
Change @irrigation.next to return date
Update Report.next_irrigation to use dates instead of datetime, display cell borders, and show next_irrigation first
Add CurrentEt model
Update rake import task to include current_et
Add CurrentEt to @irrigation.next_irrigation
Add SoilClass model and corresponding rake import:soil_class
Add mad (management allowed depletion) to @irrigation.next_irrigation