Future::then to Future::thenValue
Future::then to Future::thenValue

Summary: Future::then to Future::thenValue to remove calls to deprecated functions.

Reviewed By: Orvid

Differential Revision: D10364875

fbshipit-source-id: 9859b55792a6495738429c04666b967806ff27cc

facebook/wangle,facebook/wangle,facebook/wangle