also test against php 5.5 on travis ci
also test against php 5.5 on travis ci

jenniferyien/cache,doctrine/cache,robocoder/cache,robocoder/cache,mpdude/cache,piwik/cache,guilhermeblanco/cache,Rican7/cache,jeskew/cache,Ocramius/cache,doktorsitesi/cache,doktorsitesi/cache,Tobion/cache,anonpain/cache