MAGETWO-32363: Update composer files for PHP 5.6

- Change based on CR suggestion.

Author: Safwan Khan

.travis.yml

@@ -19,8 +19,6 @@ matrix:
       env: TEST_SUITE=static_phpcs
     - php: 5.6
       env: TEST_SUITE=static_annotation
-  allow_failures:
-    - php: 5.6
 before_install:
   - sudo apt-get update -qq
   - sudo apt-get install -y -qq postfix