Use join instead of a busy wait in Framework. Use set instead of setAndGet on
an AtomicReference, because wasn't using the gotten value, in Framework.
Merge branch 'master' of https://github.com/scalatest/scalatest
Synchronize access to the body of the NoArg in case different threads
are involved. This could happen if someone uses NoArg in a suite that
mixes in ParallelTestExecution. Otherwise it would normally be the
same thread that constructs the test runs the test.