#382 Add Twitter streaming demo, and #129 (all streaming demos), with th...

#382 Add Twitter streaming demo
#129 (all streaming demos)
And addition of a runner script and finished demo setup, config and run documentation.
Plus some sweet build changes for demos and slimmed down the demo dependencies for spark-submit in the near future of a particular streaming (kafka, twitter...)
Thanks, yeah this is a push I did while work was in progress, to show something to a team mate :)