Merge pull request #2819 from fredemmott/hhvm-travis

Enable HHVM on travis-ci
diff --git a/.travis.yml b/.travis.yml
index fa9d5e5..27fe3c6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,7 @@
   - 5.3
   - 5.4
   - 5.5
+  - hhvm
   
 env:
   - DB=mysql
@@ -22,6 +23,10 @@
 
 script: phpunit --coverage-text --configuration tests/travis/$DB.phpunit.xml
 
+matrix:
+  allow_failures:
+    - php: hhvm
+
 branches:
   only:
     - develop