[travis-ci] Workaround composer cache invalidation
[travis-ci] Workaround composer cache invalidation

see: https://github.com/travis-ci/travis-ci/issues/2435

turrsis/zend-mvc,ezimuel/zend-mvc,turrsis/zend-mvc,MadCat34/zend-mvc,svycka/zend-mvc,MadCat34/zend-mvc,ezimuel/zend-mvc,svycka/zend-mvc