added FileSetObject
refactored ZipFunction to use FileBuilder
refactored NewFileFunction to use FileBuilder
refactored JarFunction to use FileBuilder
refactored TaskExecutorTest to use FileBuilder
removed Sandbox.createFile()
refactored Unzipper/UnzipFunction
added FakeObjectsDb
reused FakeObjectsDb in tests
added ForwardingOutputStream
refactored OutputClassFile/SandboxedJavaFileManager to use FileBuilder
added FakeObjectsDb.createFileContainingItsPath()
refactored FilesFunction to use FileSetBuilder
refactored FileSetBuilder to use ObjectsDb instead of MutableStoredFileSet