some final renamings for 4.0

[Allen Gilliland]

I have a couple final class renamings I'd like to do ...
Roller -> Weblogger
RollerFactory -> WebloggerFactory
RollerImpl -> WebloggerImpl

This just makes the most sense now that 'Roller' is the name referring 
to the entire project and 'Weblogger' and 'Planet' are the actual 
application specific names.

objections?

-- Allen