Tech platform Onspring is no stranger to the fast track. The Overland Park company has doubled, even tripled, its revenue every year since its launch in 2012. Its staff included 15 at this point last year — now, it’s at 32 and still hiring. “Our struggles are now less about how to land customers and revenue, and more about how to find employees,” co-founder and CTO Chad Kreimendahl said. With…