Bug 701838 - Work around a semantic API break in GObject

Bug 701838 - Work around a semantic API break in GObject

Recent versions of GObject fire critical messages if properties are
installed outside of class initializers (causing all of EDS tests to
fail).  This patch adds some class data and initializes the class in
the dynamic subclass initializer.

Note that the class data which should normally be freed in the class
finalizer is not freed, since it is a static type the finalizer will
never run (and GLib also takes the liberty of firing critical messages
for specifying a class finalizer).