Memory Leak in the JWD

The JWD workflow designer is leaking a reference to its ClassLoader from the MetalLookAndFeel.

(see https://extranet.atlassian.com/x/9Bf4dg for how to find the leak)

Basically, when JWD is loaded it will set "MetalLookAndFeel" up so that it can correctly render the workflow image. The problem is that MetalLookAndFeel keeps a static cache of the sun.awt.AppContext which eventually has a reference to a java.awt.EventQueue. The java.awt.EventQueue caches the TCC of the thread that created it which in this case is the Bundle Classloader of the JWD plugin. This is a problem because MetalLookAndFeel comes from the system classloader and is only initialised once which means that it keeps a reference to the Bundle Classloader of the first JWD around.