Have Travis-CI also test on beta.

SimonSapin · SimonSapin · commit a11ef73bd47f · 2015-04-05T22:45:46.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,5 +1,8 @@
 sudo: false
 language: rust
+rust:
+  - nightly
+  - 1.0.0-beta
 
 script:
   - cargo build --verbose
