Fixed Travis build composer dependencies

.travis.yml

@@ -9,13 +9,19 @@ env:
   - SYMFONY_VERSION="2.8.*"
   - SYMFONY_VERSION="3.3.*"
   - SYMFONY_VERSION="3.4.x-dev"
+  - SYMFONY_VERSION="4.0.x-dev"
 
 matrix:
   exclude:
+    # Symfony >= 3.4 PHP requirement is ^7.1.3
     - php: 7.0
-      env: SYMFONY_VERSION="3.4.x-dev" # Symfony >= 3.4 PHP requirement is ^7.1.3
+      env: SYMFONY_VERSION="3.4.x-dev"
+    - php: 7.0
+      env: SYMFONY_VERSION="4.0.x-dev"
   allow_failures:
-    - env: SYMFONY_VERSION="3.4.x-dev" # Symfony unstable version, allowed to fail
+    # Symfony unstable versions, allowed to fail
+    - env: SYMFONY_VERSION="3.4.x-dev"
+    - env: SYMFONY_VERSION="4.0.x-dev"
 
 sudo: false
 
@@ -25,8 +31,7 @@ cache:
 
 before_install:
   - composer selfupdate
-  - if [ "$SYMFONY_VERSION" != "" ]; then composer require "symfony/framework-bundle:${SYMFONY_VERSION}" --no-update; composer require "symfony/security-bundle:${SYMFONY_VERSION}" --no-update;  composer require --dev "symfony/yaml:${SYMFONY_VERSION}" --no-update; fi;
-  - if [ "$SYMFONY_VERSION" == "3.4.x-dev" ]; then composer require "symfony/cache:${SYMFONY_VERSION}" --no-update; fi;
+  - if [ "$SYMFONY_VERSION" != "" ]; then composer require "symfony/symfony:${SYMFONY_VERSION}" --no-update; fi;
 
 install: composer update --prefer-dist --no-interaction $COMPOSER_FLAGS