[composer] Raise php version to 5.5
[composer] Raise php version to 5.5

As discussed in IRC meeting 2015-06-04

zendframework/zend-paginator,zendframework/zend-paginator,Maks3w/zend-paginator,MadCat34/zend-paginator,Maks3w/zend-paginator,MadCat34/zend-paginator