Support non-ASCII UTF-8 keys
Support non-ASCII UTF-8 keys

Summary: This diff enables mcrouter to handle (some? all?) non-ASCII UTF-8 keys without segfaulting.

Reviewed By: pavlo-fb

Differential Revision: D3372845

fbshipit-source-id: 52609eb597069c32de13232ebb830d86b6af4250

facebook/mcrouter,facebook/mcrouter,facebook/mcrouter,yqzhang/mcrouter,yqzhang/mcrouter,yqzhang/mcrouter,yqzhang/mcrouter,facebook/mcrouter