I just updated my JDK to the JDK 1.8 because i couldnt find the jfxrt.jar needed by java FX in the 1.7 version.
I downloaded the JDK from here: http://www.oracle.com/tec
For me on OSX it's under jdk1.8.0_05.jdk/Contents/Home/jre/lib/ext/jfxrt.jar. I'd guess it's in an analogous place on your machine. Try /usr/java/jdk1.8.0_05/jre/lib/ext/jfxrt.jar
jdk1.8.0_05.jdk/Contents/Home/jre/lib/ext/jfxrt.jar
/usr/java/jdk1.8.0_05/jre/lib/ext/jfxrt.jar