tell travis this only works on nightly

Gankra · Gankra · commit 71f2de20b039 · 2015-06-16T18:45:34.000-07:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,4 +1,6 @@
 language: rust
+rust:
+	- nightly
 sudo: false
 matrix:
   include:
