Update travis.yml following the removal of sudo by default

See http://blog.travis-ci.com/2015-03-31-docker-default-on-the-way/

.travis.yml

@@ -78,6 +78,8 @@ matrix:
     - php: hhvm
       env: TEST_SUITE=AngularJSTests MYSQL_ADAPTER=PDO_MYSQL
 
+sudo: required
+
 script: $PIWIK_ROOT_DIR/tests/travis/travis.sh
 
 before_install:

plugins/TestRunner/templates/travis.yml.twig

@@ -61,6 +61,8 @@ matrix:
   {{ existingMatrix|trim|raw }}
 {% endif %}
 
+sudo: required
+
 script: {{ travisShScriptLocation }}
 
 before_install: