appsdk-bump-app-catalog 279 bumping sdk to 1475-ad8b4fe

sdk commit: RallySoftware/appsdk@50cf22a47fc119176bba0a9b9b6a5d7d0a55d010
author: Ashly Simmons
message: fixing treegrid column header trigger position

sdk commit: RallySoftware/appsdk@6f94e170f39c132f122f20f7af8546f1d504220b
author: Ashly Simmons
message: DE19946: IE10 and IE11 behavior with dropdown fields on Ext2 & Ext4.2

sdk commit: RallySoftware/appsdk@ad8b4fef2ec708c96691fd2f86c2ccc463b37fee
author: Ashly Simmons and Erika Brice
message: DE19946: IE10 and IE11 need x4-ie class