Output jUnit XML results if test.xml_output is set
Allow ignoring unit test failures by setting test.haltonfailure=no

If test.haltonfailure is set to yes, jUnit will only run until the first
failure. When using the XML output you usually want to run all the
tests, and ignoring test failures seems to be the only way to do that.
Enable test.xml_output=true by default, configure the output directory properly