Merge banana-unsupported-type-exception-7663

Author: wolfgang61, exarkun
Reviewer: exarkun
Fixes: #7663

Change Banana's unsupported type exception message to include the type of the
unsupported object.


git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/trunk@43213 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb