Fix build status images

The repository was moved, update the links.
diff --git a/README.md b/README.md
index cf4a2ab..e4af990 100644
--- a/README.md
+++ b/README.md
@@ -7,8 +7,8 @@
 
 |Branch      |Status   |
 |------------|---------|
-|master      | [![Build Status](https://travis-ci.org/Cyan4973/zstd.svg?branch=master)](https://travis-ci.org/Cyan4973/zstd) |
-|dev         | [![Build Status](https://travis-ci.org/Cyan4973/zstd.svg?branch=dev)](https://travis-ci.org/Cyan4973/zstd) |
+|master      | [![Build Status](https://travis-ci.org/facebook/zstd.svg?branch=master)](https://travis-ci.org/facebook/zstd) |
+|dev         | [![Build Status](https://travis-ci.org/facebook/zstd.svg?branch=dev)](https://travis-ci.org/facebook/zstd) |
 
 As a reference, several fast compression algorithms were tested and compared on a Core i7-3930K CPU @ 4.5GHz, using [lzbench], an open-source in-memory benchmark by @inikep compiled with gcc 5.4.0, with the [Silesia compression corpus].