Add explicit mongo start

.travis.yml

@@ -11,7 +11,7 @@ env:
     - DRIVER_VERSION="stable"
     - ADAPTER_VERSION="^1.0.0"
 
-sudo: false
+sudo: true
 
 services:
   - mongodb
@@ -41,6 +41,7 @@ before_script:
   - if [[ ${TRAVIS_PHP_VERSION:0:2} == "7." ]]; then pecl install -f mongodb-${DRIVER_VERSION}; fi
   - if [[ ${TRAVIS_PHP_VERSION:0:2} == "7." ]]; then composer config "platform.ext-mongo" "1.6.16" && composer require "alcaeus/mongo-php-adapter=${ADAPTER_VERSION}"; fi
   - mysql -e 'create database unittest;'
+  - sudo service mongod start
   - travis_retry composer self-update
   - travis_retry composer install --no-interaction