Add JavaFX samples to JDK demos bundle

It's been requested that the JavaFX samples be packaged with the JDK demos, so that the user downloads only one "demos" file when he wants to access Java or JavaFX demos/samples. Currently, this request applies just to JDK8.

On the JavaFX side, we are tracking with Jira Issue RT-24159 (https://javafx-jira.kenai.com/browse/RT-24159).

The JavaFX build now produces a zip file of the shipping JavaFX samples in <root>/jfx/artifacts/bundles/export-for-cobundle/javafx-samples-for-cobundle.zip

The file javafx-samples-for-cobundle.zip unzips to:

javafx_samples/

and the content of our existing JavaFX samples zip file that users can download today is all under this directory.

To complete the final goal, we need to ask that the JDK8 build be adjusted to copy the content of javafx-samples-for-cobundle.zip into the JDK demo bundle.