Added some missing flags, that I needed for my app, in the jfxDeploy task: offlineAllowed, updateMode, codebase, and all the shortcut icon properties

Just a quick fix to add some missing properties I desperately needed in the generated JNLP file. If you want, I can map all the properties you didn't have the time to add. Just tell me and I'll do it ASAP.

Thanks for the plugin!