upgrade oss sai to 1.7.0
upgrade oss sai to 1.7.0

Summary:
moving to 1.7.0 for open source github sai

also build fake with 1.7.0

Differential Revision: D26152792

fbshipit-source-id: 02e7bfb218d200666e506e3115ee8f5dba5ece0a

facebook/wangle,facebook/wangle,facebook/wangle