eth_getBlockByHash and block hash mapping functionality (#114)

* Set up block hash to height mapping storage and fixed linting issues

* fix typos

* Set up module query for block height

* fix bug with block mappings and implemented get block by hash

* Fix other consensus hash references

rpc/args/send_tx.go

@@ -19,4 +19,4 @@ type SendTxArgs struct {
 	// newer name and should be preferred by clients.
 	Data  *hexutil.Bytes `json:"data"`
 	Input *hexutil.Bytes `json:"input"`
-}
+}