Review for JDK-8043060 - First Impl for JEP-208 Packager Imrpovments

[Danno Ferrin]

Kevin, Steve,

Please review this first implementation of the features for JEP-208, tracked on bugs.openjdk.java.net as JDK-8043060.  There are some changes to the build support classes to support compiling Mac ".mm" files as well as some platform specific flags added tot he platform .gradles in buildSrc, so a +1 (or directions for improvement) from the build masters would be appreciated.

WebRev: http://cr.openjdk.java.net/~shemnon/JDK-8043060/webrev.00/
JIRA: https://bugs.openjdk.java.net/browse/JDK-8043060

This patch also encompasses the following OpenJFX JIRAs (all linked in the jep), although the discussion for this webrev should be in the JDK-8043060 bug.

RT-23918	 - Native bundles: add support to create file association
RT-28833 - Single source native launcher
RT-35388 - JavaFX Packager's launcher only works with JDK not JRE
RT-36118	 - Support multiple entry points in native installer
RT-37766	 - [packager] Respect command line arguments in self contained applications
RT-37767	 - [packager] Provide friendly APIs to access User JVM Preferences
RT-37769 - [packager] Simple DMG Generation