* update transformer to able to recheck headers
* put cap on rechecking header
* integration test for recheck headers
* use enum for recheck headers param; make recheck cap configurable
* update integration tests with new test config
* update omni pkg with new recheck header column type
* update migration with new migration tool and final tweaks needed to accommodate changes in omni pkg
- Continuously parse storage diffs CSV data to read Pit contract state
- Convert ilks in database to raw bytes32 value for use in generating
storage keys dynamically
- Persist storage diffs with block number and hash for validation
- fetches logs from all three price feeds in one query
- assumes eth/usd price feed will be updated to include LogValue event
- updates transformers to run separate from header sync