Use php7.0 docker image and install composer manually

.gitlab-ci.yml

@@ -18,15 +18,19 @@ stages:
 
 build:
     stage: build
-    image: composer
+    image: php:7.0-alpine
     variables:
         GIT_STRATEGY: "clone"
         GIT_SUBMODULE_STRATEGY: "recursive"
+    before_script:
+        - apk add bash --no-cache
+        - apk add git --update
+        - curl https://getcomposer.org/composer.phar -o composer.phar --silent
+        - chmod +x composer.phar
     script:
-        - composer config store-auths false
-        - composer config platform.php 7.0
-        - composer config http-basic.git-t3o.typo3.org gitlab-ci-token ${CI_BUILD_TOKEN}
-        - composer install
+        - ./composer.phar config store-auths false
+        - ./composer.phar config http-basic.git-t3o.typo3.org gitlab-ci-token ${CI_BUILD_TOKEN}
+        - ./composer.phar install
     artifacts:
         paths:
             - ./