appsdk-bump-app-catalog 323 bumping sdk to 1591-a3ff1cb

sdk commit: RallySoftware/appsdk@2c41e13100d6fb8cd09cd53b92d8de6a4a0377e5
author: Matt Greer and Doug Diehnelt
message: S60917 -- Define and implement the basic set of metrics needed for /iterationstatus

sdk commit: RallySoftware/appsdk@a3ff1cbff13dfcf57aa5755843c1607d1a094c20
author: Jeff Ellis
message: Revert "S58696 Changed required field styling and behavior."