Have Travis test on more Rust versions

SimonSapin · SimonSapin · commit e7a98e32949a · 2016-02-22T15:38:04.000+01:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,5 +1,13 @@
 language: rust
-rust: nightly
+rust:
+ # Jemalloc prefixing change between these two versions
+ - nightly-2016-02-14
+ - nightly-2016-02-17
+
+ - nightly
+ - beta
+ - stable
+
 notifications:
   webhooks: http://build.servo.org:54856/travis
 
