Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=52323
Add support for code coverage with Cobertura (disabled by default) when running the unit tests

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1538534 13f79535-47bb-0310-9956-ffa450edef68