#202 allow remote debugging an intetegration test 

using a command like the following:

```mvn test -Dtest=SimpleTest#oracle_java_6 -DprocessorIntegrationTest.debug=true```

The ```-Dtest=<classPattern>#<methodPattern>``` is plain vanilla Surefire (although I had to pin down the usage of the junit47-provider in the surefire config, see parent/pom.xml), as [documented on the surefire page](http://maven.apache.org/surefire/maven-surefire-plugin/examples/single-test.html).

The new option ```-DprocessorIntegrationTest.debug=true``` causes one of these two things:
* if the test case uses Toolchains (i.e. lets the compiler use a different javac than the one running the current process), then a profile is activated that tells the compiler plugin to fork that javac execution with these remote-debug arguments: ```-Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000```
* if the test case does not use Toolchains, the Maven Verifer is forced to be executed in a forked process, whereas the implementation there would call ```mvnDebug``` instead of ```mvn``` - typically, that should result in the same remote debug settings as above.

I'll create another PR for the mapstruct-org changes to document that there as well.