[reSIProcate] template hoists

[david Butcher <david@xxxxxxxxxxxxxx>]

I checked in rewrites of ContentsFactory and ParserCategory to push code out of
the template into a base class.

I tested within resiprocate, but was unable to test at the application level
(long boring story). Let me know if horrible things happen to your apps. I
don't expect trouble. No interfaces were harmed.

david