Fix quartzplugin compilation in setup.py (OSX only)

Since commit '50531e312212100c6b5a12fbc5ef8a4f576be4ca' which belongs
to release v0.5.3 it is necessary to compile the quartz plugin with
AppKit framework. Include this framework in the setup.py based build
system.

Change-Id: I68bb3401d6c9734288c924e66e8400d18e1d0e6a
Reviewed-on: https://iffwww.iff.kfa-juelich.de/review/59
Reviewed-by: Christian Felder <c.felder@fz-juelich.de>
Reviewed-by: Josef Heinen <j.heinen@fz-juelich.de>