Merge pull request #85 from petertseng/rust-versions

travis: test beta and nightly

Author: EduardoBautista

.travis.yml

@@ -5,3 +5,10 @@ script:
 - "./bin/fetch-configlet"
 - "./bin/configlet ."
 sudo: false
+rust:
+  - stable
+  - beta
+  - nightly
+matrix:
+  allow_failures:
+    - rust: nightly