Update travis url in README

Author: alexcrichton

README.md

@@ -4,7 +4,7 @@ tempdir
 A Rust library for creating a temporary directory and deleting its entire
 contents when the directory is dropped.
 
-[![Build Status](https://travis-ci.org/rust-lang/tempdir.svg?branch=master)](https://travis-ci.org/rust-lang/tempdir)
+[![Build Status](https://travis-ci.org/rust-lang-nursery/tempdir.svg?branch=master)](https://travis-ci.org/rust-lang-nursery/tempdir)
 
 [Documentation](https://doc.rust-lang.org/tempdir)