Exceptional parallel execution on @NotThreadSafe type.

We want to execute tests in parallel.
 In some cases some tests want to be executed in a single Thread instance.
 For instance I am using Embedded Container OpenEJB which is singleton, thus does not support parallelism.
 Other tests want to be executed in parallel anyway.
 This simple principle avoids parallel execution in an elegant way in src/test/java.
Why not primarily or at least also supporting ```javax.annotation.NotThreadSafe```? The JSR305 annotations are pretty wide spread out there. Perhaps you can implement it in a way that doesn't require either of the two variants on the classpath of Surefire by using Class.forName once on each, catching the ClassNotFoundException. We do it in a similar way in the TestNG provider where we check for JUnit annotations.