Have our PollingDataStream.now default to False.
Have our PollingDataStream.now default to False.

When :prop:`PollingDataStream.now` is True, Twisted will run it the DataStream
immediately, before exiting __init__.  This causes the rest of the hub to
block, waiting for this job to finish.  Setting it to False will cause it to
run initially after :prop:`PollingDataStream.frequency` seconds, asynchronously.

ralphbean/moksha,ralphbean/moksha,lmacken/moksha,pombredanne/moksha,lmacken/moksha,ralphbean/moksha,pombredanne/moksha,mokshaproject/moksha,pombredanne/moksha,pombredanne/moksha,mokshaproject/moksha,lmacken/moksha,mokshaproject/moksha,mokshaproject/moksha