drop php 5.3 from travis build matrix
drop php 5.3 from travis build matrix

BenMorel/dbal,kimhemsoe/dbal,DHager/dbal,lafourchette/dbal,vutung2311/dbal,deeky666/dbal,helicon-os/doctrine-dbal,v-bartusevicius/dbal,AlexDpy/dbal,AlexDpy/dbal,deeky666/dbal,drieschel/dbal,kimhemsoe/dbal,lafourchette/dbal,stchr/dbal,stchr/dbal,gencer/dbal,mikeSimonson/dbal,DHager/dbal,BenMorel/dbal,vutung2311/dbal,v-bartusevicius/dbal,mRoca/dbal,vortgo/dbal,doctrine/dbal,doctrine/dbal,lcobucci/dbal,mRoca/dbal,lcobucci/dbal,stof/dbal,vortgo/dbal,stof/dbal,mikeSimonson/dbal,drieschel/dbal,Tobion/dbal,gencer/dbal,helicon-os/doctrine-dbal,Tobion/dbal,bspeterson/dbal,bspeterson/dbal