Replace Future<T>::getTry with Future<T>::result
Replace Future<T>::getTry with Future<T>::result

Summary:
Replace calls to Future<T>::getTry() with Future<T>::result().

This change is behaviour-neutral. It enables us to make the behavior of getTry
match expectations and be blocking, like get, and r-value qualfiied, like
SemiFuture<T>::getTry().

Reviewed By: yfeldblum

Differential Revision: D22535786

fbshipit-source-id: 94746be714bcff5da80d2456195f571cd19261c6

facebook/wangle,facebook/wangle,facebook/wangle