Add missing license header for runtime.rs (#8252)

* Add missing license header for runtime.rs

* Update year

ethcore/wasm/src/runtime.rs

@@ -1,3 +1,19 @@
+// Copyright 2015-2018 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
 use ethereum_types::{U256, H256, Address};
 use vm::{self, CallType};
 use wasmi::{self, MemoryRef, RuntimeArgs, RuntimeValue, Error as InterpreterError, Trap, TrapKind};