update for 2013 01 06 - prep for multiple bidders

added a master redis checker class to get connection params for the
master redis, and check that the link is up. added code to make use of
the master writer (self.c_w in the bidder) for all writes/deletes. moved
ident update code into the bidder.
made all the RequestHandlers a subclass of new BaseHandler which
overrides the _handle_request_exception method mainly to trigger a
shutdown mode upon an unhandled exception.
changes in teardown (stop_tornadoes) code to remove iden