Decouple log extraction from transformer delegation

- limit missing headers results set to 100 so that extraction doesn't
  excessively block delegation
- wrap checked headers functions in repository struct
- move storage repository to factory, to correspond with event
  repository path
- remove unused files
- reformat sql
- remove line breaks in imports

libraries/shared/fetcher/log_fetcher.go

@@ -26,6 +26,7 @@ import (
 
 type ILogFetcher interface {
 	FetchLogs(contractAddresses []common.Address, topics []common.Hash, missingHeader core.Header) ([]types.Log, error)
+	// TODO Extend FetchLogs for doing several blocks at a time
 }
 
 type LogFetcher struct {