appsdk-bump-app-catalog 422 bumping sdk to 1875-a4de1bb

sdk commit: RallySoftware/appsdk@a4de1bb43880d785c6abff1c4172c8ddaa5273d4
author: Robb Lee and Dave Thompson
message: DE20512: refactored TreeGrid to handle ranking using a mixin.  Fix for defect 20572 handled bulk of issue.