WIP: Upgrade JavaFX support to v.8.0_u20

Removed wrappers for methods in SwingFXUtils that are no longer public and
broke compilation. Code compiles but some test do not pass due to new properties
introduced in v.8.0_u20 and changes in how some `null` arguments are interpreted
in JavaFX.
Upgrade Scala 11 and ScalaTest to latest versions.