change board decision to not be an incoming mail (#4392)

src/pfwbged/basecontent/types.py

@@ -61,14 +61,14 @@ class Agenda(PfwbBaseDocument):
     implements(IAgenda)
 
 
-class IBoardDecision(IDmsIncomingMail):
+class IBoardDecision(IPfwbBaseDocument):
     """ """
     meeting_date = schema.Date(
             title=_(u'Meeting Date'),
             required=False)
 
 
-class BoardDecision(DmsIncomingMail):
+class BoardDecision(PfwbBaseDocument):
     implements(IBoardDecision)