[Font] Provide font rendering hints to improve quality of text rendering

As evidenced by the screenshots in http://pixelduke.wordpress.com/ blog posts about JMetro, javafx as noticeably poor font rendering visuals. The most recent screenshots were taken on a windows 8.1 machine and the older ones on windows 7, using Segoe UI (windows 7 & 8 system font), both exhibit poor font rendering visuals especially the header text which is bigger.

The source code for the app can be found on: https://github.com/JFXtras/jfxtras-styles/tree/master/src/jmetro8