Implement Event Stream Processing (ESP) module

[groganz]

• [x] Include Google Protocol Buffers (protobufs)
• [x] Generate classes based on protobufs per module
  • [ ] Add command to install/update scripts
• [x] REST API for event data consumption based on protobuf classes per module
  • [ ] Implement + document REST API response
• [x] Validate REST API payload with protobuf
• [ ] Check if module and event name actually exist as provided in event URI
• [ ] Allow default consumption of event properties without protobuf validation
• [x] Write REST API payload into Elasticsearch
  • [x] Create index per package
• [ ] Map event to CampaignChain Location or Operation
  • [ ] Location::identifier must not be empty (either ID or URL)
  • [ ] Operation must have an identifier
• [ ] Automatically collect data of common fields
• [ ] Client-side JavaScript library to emit event data
• [ ] Rewrite existing report jobs and visualizations to use ESP API
• [ ] Document protobuf: https://github.com/pseudomuto/protoc-gen-doc
• [ ] Throw exception if not JSON in body
• [x] Log errors
• [ ] Document installation of Elasticsearch and Kibana
• [ ] Ensure with composer that Elasticsearch and Kibana are installed