Fix for bug 709122 - Do not wrap __class__ object from plugins' methods
Fix for bug 709122 - Do not wrap __class__ object from plugins' methods

This is a temporary solution of this bug. In a mid-term we would like
to move the plugins' architecture to use a composite with a proxy like
accessor to wrap callable objects from the plugins as it was suggested
in https://bugzilla.gnome.org/show_bug.cgi?id=723081#c4

GNOME/accerciser,GNOME/accerciser