block cleanup (#9117)

* blockchain insert expects owned block instead of block reference

* reduce a number of times a block is deserialized

* removed cached uncle_bytes from block

* removed is_finalized from OpenBlock

* removed unused parity_machine::WithMetadata trait

* removed commented out code

* remove unused metadata from block

* remove unused metadata from block

* BlockDetails extras may have at most 5 elements

ethcore/src/verification/verification.rs

@@ -467,7 +467,6 @@ mod tests {
 					parent: header.parent_hash().clone(),
 					children: Vec::new(),
 					is_finalized: false,
-					metadata: None,
 				}
 			})
 		}