Exclude vendor/ from ReleaseCheckList <?php test and remove setupProfilerXHProf that are no longer necessary.

Get xhprof integration to work. Only setup xhprof once per php execution and correctly aggregate xhprof runs (xhprof aggregation will always normalize so we must aggregate ourselves).

Enables code coverage reports using coveralls.io

enable travis to run tests on PHP 5.6 to see if a reported problem only occurs on 5.6. It will be released soon

refs #5970 make sure to reload the same page if user clicks on a date in the evolution chart, even if the metric was changed

refs #4224, #4302 - added code coverage report using coveralls.io