Add composer 1.5.6, remove composer 1.5.5
Add composer 1.5.6, remove composer 1.5.5

source url: https://getcomposer.org/download/1.5.6/composer.phar
source sha256: 25e75d72818c4f1d46b3ae47a8deaaf4ef25c87198329d4a6ee53601b00459e5

[#153780580]

cloudfoundry/php-buildpack,cloudfoundry/php-buildpack,Orange-OpenSource/cf-php-build-pack,cloudfoundry/php-buildpack,Orange-OpenSource/cf-php-build-pack,cloudfoundry/php-buildpack,cloudfoundry/php-buildpack,cf-identity/php-buildpack,cloudfoundry/php-buildpack,Orange-OpenSource/cf-php-build-pack,cf-identity/php-buildpack,cf-identity/php-buildpack,cf-identity/php-buildpack,cloudfoundry/php-buildpack,cf-identity/php-buildpack,cf-identity/php-buildpack,cf-identity/php-buildpack