Revert "Revert "Update to 5.5.15 and 5.4.31""

This reverts commit 8da8461a6650bd278d8399c11a225d87440cf9ee.
Revert "Revert "Add php 5.6RC2""

This reverts commit af38eeb9f801266385a9bca01577fe7e2be932dd.