Invoke coveralls with php
Invoke coveralls with php

Change invocation of php-coveralls to use the php executable as
documented in their README. This will ensure that it still works even
when the executable bit is not set on the file for any reason.

See https://github.com/php-coveralls/php-coveralls/blob/2.0/README.md#travis-ci

tux-rampage/zend-di,zendframework/zend-di