Add quotes around $JAVA

Allows script to run when JAVA_HOME has spaces in it (for instance "/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home" which is common on OSX). Without this change, the error reported by the script is "./scripts/RapidMinerGUI: line 170: /Library/Internet: No such file or directory"
Merge pull request #1 from motin/patch-1

Add quotes around $JAVA