CSV Output from CLI

[jmoussa]

Some users will just want a dump of whatever the pipeline outputs.
In this scenario we're assuming the user has already loaded up their MongoDB instance with data, and this will query that data and return back results in csv form.

To be considered:

• Column layout/structure for csv?
• Instead of pulling from the db, start the pipeline and output a csv file for every n tweets
  • add a sink-to-CSV function to the pipeline as an optional pipeline run type)