composer memory limit

Adding COMPOSER_MEMORY_LIMIT=-1 to composer update

Author: npotier

.travis.yml

@@ -37,7 +37,7 @@ before_script:
 
 install:
   - travis_retry composer self-update
-  - travis_retry composer update ${COMPOSER_FLAGS} --no-interaction
+  - COMPOSER_MEMORY_LIMIT=-1 travis_retry composer update ${COMPOSER_FLAGS} --no-interaction
   - curl -s http://getcomposer.org/installer | php
   - php composer.phar install --dev --no-interaction