This adds the custom_wsgi_process_options parameter to
the horizon class that is passed down to the
horizon::wsgi::apache class when configure_apache is
set to true.
Change-Id: I986aeb9766a777eaf82f1f2fccfed95b380dc4c7
(cherry picked from commit cd5216f5a59835485869f6d352e92c7473de3c5d)