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/encoded.rs

@@ -222,6 +222,11 @@ impl Block {
 
 	/// Consume the view and return the raw bytes.
 	pub fn into_inner(self) -> Vec<u8> { self.0 }
+
+	/// Returns the reference to slice of bytes
+	pub fn raw(&self) -> &[u8] {
+		&self.0
+	}
 }
 
 // forwarders to borrowed header view.