[travis-ci] Composer install --ignore-platform-reqs
[travis-ci] Composer install --ignore-platform-reqs

Remove platform constraint requirements when install. Tests already skip the execution if the required plafform requirement is not present

akrabat/zend-inputfilter,stefanotorresi/zend-inputfilter,MadCat34/zend-inputfilter,Maks3w/zend-inputfilter,weierophinney/zend-inputfilter,Blinden/zend-inputfilter,akomm/zend-inputfilter,zendframework/zend-inputfilter,zf2timo/zend-inputfilter