Use new Travis infrastructure. Test with PHP7.

.travis.yml

@@ -1,10 +1,18 @@
 language: php
 
+sudo: false
+
+cache:
+  directories:
+    - $HOME/.composer/cache
+
 php:
   - 5.4
   - 5.5
   - 5.6
+  - nightly
   - hhvm
+  - hhvm-nightly
 
 matrix:
     include:
@@ -19,6 +27,9 @@ matrix:
     allow_failures:
         - php: 5.5
           env: SYMFONY_VERSION='dev-master'
+        - php: nightly
+        - php: hhvm-nightly
+    fast_finish: true
 
 before_script:
     - composer self-update