Tweak Travis config

Author: dunglas

.travis.yml

@@ -1,17 +1,25 @@
-language: php
+sudo: false
+
+cache:
+  directories:
+    - $HOME/.composer/cache
 
 php:
-  - 5.4
-  - 5.5
-  - 5.6
-  - hhvm
+    - 5.4
+    - 5.5
+    - 5.6
+    - nightly
+    - hhvm
+    - hhvm-nightly
 
 matrix:
     allow_failures:
-        - php: hhvm
+        - php: nightly
+        - php: hhvm-nightly
+    fast_finish: true
 
 before_script:
-  - composer install --dev
+  - composer install
 
 script:
   - tests/run-tests.sh