1. Updates or replaces outdated dependencies (eg, replacing a version of the Prysm client with the latest zrnt).
2. Add support for parsing Bellatrix-era BeaconState and BeaconBlocks
3. Adds flags for toggling the processing of BeaconBlocks and BeaconState. This is particularly important because processing and storing the BeaconState at this time would be too expensive to really do (see: Temporarily disable BeaconState indexing #75 and [Feature] Reduce the Amount of DB Space the Beacon Chain Needs #71)
4. Fixes flaky event handling. The previous code would not reconnect in the case of errors with the SSE connection. This enables automatic reconnection in the case of error (default in the updated v2 SSE library dependency), and also adds a timeout so that if no event is received in 2.5x the block time, the SSE connection is closed and re-established.
5. Other refactoring and cleanup (eg, changing the type of slot from int to Slot (uint64)).
* -- Intermediary Commit --
Just want to commit my code over the weekend, in case I spill coffee on my workstation.
* Create DB models ready for write.
* Handle SSE events
* Update ref for stack-orchestrator
* Use env in one place only.
* Boot Application on PR
* Update syntax
* Update syntax
* Correct command
* Use bash instead of sh
* Use until instead of while
* Make linter happy and check sse subscription err
* Handle Reorgs - Untested
