ResourcesRegistry was erroring out during API doc building in Review

Board due to Sphinx's function inspection in autodoc. It was trying to

do a getattr() of __get__, __set__, and other similar methods,

which was turning into resource module lookups. That clearly failed, and

the errors bubbled up and became warnings during doc building. This has

been fixed to immediately call the parent method if encountering such a

function.
It also had a scoping issue with errors from an exception in Python 3.

There was an assumption that later code could get access to the

exception from a previous except .. as e block, but that's not the

case in Python 3. We now set a properly-scoped variable to the last

exception for later logging.

No longer saw errors during doc building.
Tested that the error messages were including the right exception

information on Python 2.7 and 3.