Move to new travis containerised infrastructure

.travis.yml

@@ -1,5 +1,12 @@
 language: php
 
+sudo: false
+
+addons:
+  apt:
+    packages:
+      - tidy
+
 env:
   global:
     - DB=MYSQL CORE_RELEASE=3.1
@@ -16,11 +23,9 @@ matrix:
       env: DB=MYSQL
     - php: 5.3
       env: DB=MYSQL
-    - php: hhvm-nightly
+    - php: hhvm
       env: DB=MYSQL
       before_install:
-        - sudo apt-get update -qq
-        - sudo apt-get install -y tidy
 
 
 before_script: