Retry if composer fails (github)

Author: michaelcullum

.travis.yml

@@ -42,7 +42,7 @@ branches:
     - /^release-.*$/
 
 install:
-  - composer install --dev --no-interaction --prefer-source
+  - travis_retry composer install --dev --no-interaction --prefer-source
   - travis/prepare-phpbb.sh $EXTNAME $PHPBB_BRANCH
   - cd ../../phpBB3
   - travis/prepare-extension.sh $EXTNAME $PHPBB_BRANCH