Validate signature in Tx queue (#1068)

* moving deps to ethcore/hyper and bumping jsonrpc-http-server version

* Validate signature in tx queue

miner/src/transaction_queue.rs

@@ -442,6 +442,8 @@ impl TransactionQueue {
 			}));
 		}
 
+		try!(tx.check_low_s());
+
 		if tx.gas > self.gas_limit {
 			trace!(target: "miner",
 				"Dropping transaction above gas limit: {:?} ({} > {})",
@@ -655,7 +657,6 @@ impl TransactionQueue {
 			return Err(TransactionError::AlreadyImported);
 		}
 
-
 		let address = tx.sender();
 		let nonce = tx.nonce();