Fix HHVM build for now again and ignore future HHVM build errors

Author: clue

.travis.yml

@@ -1,15 +1,26 @@
 language: php
+
 php:
   - 5.3
   - 5.6
-  - hhvm
+
+# also test against HHVM, but require "trusty" and ignore errors
+matrix:
+  include:
+    - php: hhvm
+      dist: trusty
+  allow_failures:
+    - php: hhvm
+
 env:
   - LOGIN=username:password@localhost
+
 install:
   - sudo apt-get -qq update && sudo apt-get --no-install-recommends -qq install -y asterisk
   - sudo cp tests/username.conf /etc/asterisk/manager.d/username.conf
   - sudo /etc/init.d/asterisk reload
   - composer install --prefer-source --no-interaction
+
 script:
   - sudo /etc/init.d/asterisk status || sudo /etc/init.d/asterisk start
   - sudo /etc/init.d/asterisk status || sleep 2