Tweaked documentation. Added two code samples for ScalaTest.
Organized code samples for test into scalatest and specs subdirectories of test/code. Adjusted links on page such to match and verified it with the validate-docs target.
Cleaned up and clarified the links between the pages in the testing section.
Got the tests to run again after the code reorganization.
Ported UserServiceSpec to ScalaTest.
Ported ExampleControllerSpec to ScalaTest.
Added ScalaFunctionalTestSpec.scala, and make StackSpec.scala to work.