Tweak travis config, run tests on nightly

Author: alexcrichton

.travis.yml

@@ -1,17 +1,23 @@
 language: rust
-rust:
-  - stable
-  - beta
-  - nightly
 sudo: false
-before_script:
-  - pip install 'travis-cargo<0.2' --user && export PATH=$HOME/.local/bin:$PATH
+
+matrix:
+  include:
+    - rust: 1.18.0
+    - rust: stable
+    - rust: beta
+    - rust: nightly
+      before_script:
+        - pip install 'travis-cargo<0.2' --user && export PATH=$HOME/.local/bin:$PATH
+      script:
+        - cargo build
+        - cargo test
+        - cargo doc --no-deps
+      after_success:
+        - travis-cargo --only nightly doc-upload
+
 script:
-  - travis-cargo build
-  - travis-cargo --only nightly test
-  - cargo doc --no-deps
-after_success:
-  - travis-cargo --only nightly doc-upload
+  - cargo test
 env:
   global:
     - TRAVIS_CARGO_NIGHTLY_FEATURE=""