fix(time-utils): add missing license (#10497)

util/time-utils/src/lib.rs

@@ -1,9 +1,25 @@
+// Copyright 2015-2019 Parity Technologies (UK) Ltd.
+// This file is part of Parity Ethereum.
+
+// Parity Ethereum 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 Ethereum 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 Ethereum. If not, see <http://www.gnu.org/licenses/>.
+
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
-/// Temporary trait for `checked operations` on SystemTime until these are available in standard library
+/// Temporary trait for `checked operations` on SystemTime until these are available in the standard library
 pub trait CheckedSystemTime {
  /// Returns `Some<SystemTime>` when the result less or equal to `i32::max_value` to prevent `SystemTime` to panic because
- /// it is platform specific, possible representations are i32, i64, u64 and Duration. `None` otherwise
+ /// it is platform specific, possible representations are i32, i64, u64 or Duration. `None` otherwise
  fn checked_add(self, _d: Duration) -> Option<SystemTime>;
  /// Returns `Some<SystemTime>` when the result is successful and `None` when it is not
  fn checked_sub(self, _d: Duration) -> Option<SystemTime>;