Communication broker - part 1 / Multi-application handling interface part-2

[YooSunYoung]

I fixed some problems from #45 thanks to the communication protocol updates.

Related to #41, #43

Main changes

• Communication channel mapping per application is now done by the communication broker, beamlime.communications.broker.CommunicationBroker.
• broker follows the BeamlimeBrokerProtocol which inherits CommunicationProtocol.
• broker will get, put, consume and produce data according to the type of channel that application is subscribing to.
• data-stream configuration now has all application specs including data-reduction.
• __init__ function of BeamlimeApplicationInterface updated so that it does not need to have config as a dictionary and parse it. All specs can be dumped by **config when it's instantiated.
• You can test this with the src/beamlime//offine/offline_system_example.ipynb. It will be moved to docs later...!

TODO - Things I will continue after the vacation!

• put and poll method implementation.
• Add tests for communication interfaces.
• Add communication handles. (Currently single-process queue only. We need a blackboard, multi-processing queue and kafka, kafka interfaces are already tested but still need to implement auto-configuration part.)
• Figure out what issues we will have in multi-processing, since now all application is sharing one broker instance. (I have an idea of instance twins...!)
• Add logging into broker and data flow monitor.

[YooSunYoung]

I will merge this one since it was reviewed in other PR and will be reviewed again in the PR #53