using composer update as test command

Author: schmunk42

docker-compose.yml

@@ -1,24 +1,24 @@
 php54:
   image: jolicode/php54
-  command: sh -c 'cd /app && composer install && bin/phpunit'
+  command: sh -c 'cd /app && composer update && bin/phpunit'
   volumes:
     - ./:/app
     - /var/run/docker.sock:/var/run/docker.sock
 php55:
   image: jolicode/php55
-  command: sh -c 'cd /app && composer install && bin/phpunit'
+  command: sh -c 'cd /app && composer update && bin/phpunit'
   volumes:
     - ./:/app
     - /var/run/docker.sock:/var/run/docker.sock
 php56:
   image: phundament/php-one:5.6-fpm
-  command: sh -c 'composer install && bin/phpunit'
+  command: sh -c 'composer update && bin/phpunit'
   volumes:
     - ./:/app
     - /var/run/docker.sock:/var/run/docker.sock
 php70:
   image: phundament/php-one:7.0-fpm
-  command: sh -c 'composer install && bin/phpunit'
+  command: sh -c 'composer update && bin/phpunit'
   volumes:
     - ./:/app
     - /var/run/docker.sock:/var/run/docker.sock