Draft: Twitter v2

There are 1000 lines added 500 lines removed, but reviewing this MR hopefully still be straighforward.

I split the plugin into 4 main components. In the order of data flow: TweepyProducer, Plugin, PodQueue and ItemConsumer.

In summary, this is what they do:

• TweepyProducer spits out tweets, accounts and related media
• Plugin creates PodUpdate items out of the above mentioned objects and places them on the queue (PodQueue)
• A PodUpdate consists of create_items, create_edges and update_items, just like before.
• ItemConsumer takes 50 or less PodUpdates at a time and puts them into pod.
• PodQueue is a priority queue and it prioritizes Tweets over everything else, then Accounts, then the rest in FIFO manner.

Remaining tasks:

• Port CI tests to v2
• Sending progress updates
• Update README with how to do authentication for development
• Integrate with FE (implement Oauth2 flow, see cli/main.py)