Added PHP 5.6 and HHVM to travis.yml

I fixed the build matrix. We want to reduce the number of redundant runs

.travis.yml

@@ -3,19 +3,38 @@ php:
   - 5.3
   - 5.4
   - 5.5
+  - 5.6
+  - hhvm
+
 env:
-  - SYMFONY_VERSION="2.1.*"
-  - SYMFONY_VERSION="2.2.*"
   - SYMFONY_VERSION="2.3.*"
-  - SYMFONY_VERSION="2.4.*" SENSIO_FRAMEWORK_EXTRA_BUNDLE_VERSION="3.*"
-  - SYMFONY_VERSION="2.5.*" SENSIO_FRAMEWORK_EXTRA_BUNDLE_VERSION="3.*"
-  - SYMFONY_VERSION="dev-master" MIN_STABILITY="dev"
+
+matrix:
+  allow_failures:
+    - php: hhvm
+    - env: SYMFONY_VERSION="dev-master" MIN_STABILITY="dev"
+  include:
+    - php: 5.3
+      env: SYMFONY_VERSION="2.1.*"
+    - php: 5.5
+      env: SYMFONY_VERSION="2.1.*"
+    - php: 5.5
+      env: SYMFONY_VERSION="2.2.*"
+    - php: 5.5
+      env: SYMFONY_VERSION="2.4.*" SENSIO_FRAMEWORK_EXTRA_BUNDLE_VERSION="3.*"
+    - php: 5.5
+      env: SYMFONY_VERSION="2.5.*" SENSIO_FRAMEWORK_EXTRA_BUNDLE_VERSION="3.*"
+    - php: 5.5
+      env: SYMFONY_VERSION="dev-master" MIN_STABILITY="dev"
+
 before_script:
   - sh travis_before_build.sh
   - mkdir -p build/logs
+
 script:
   - phpunit --coverage-clover build/logs/clover.xml
-  - php vendor/bin/coveralls -v
+  - sh -c 'if [ "${TRAVIS_PHP_VERSION}" != "hhvm" ]; then php vendor/bin/coveralls -v; fi;'
+
 notifications:
   email:
     on_success: always