This doesn't need to be public
Changed some int tests to use DefaultTestExecutionResult rather than JUnitTestExecutionResult, to use whatever the default mechanism for verifying test results happens to be.
Use id instead of selector when validating metadata.
Some comments
Added some open issues to spec
Removed ModuleComponentIdentifier.getModule().
Changed ParallelTaskPlanExecutor to use the main thread to run tasks instead of having it block.

- inject an ExecutorFactory into the ParallelTaskPlanExecutor.
- inlined ExecutionOptions into TaskPlanExecutorFactory.
Added some test cases to some stories in spec.