Allow modules to validate transaction, second attempt (#2463)

* first impl

* rename origin::inherent to none

* fix

* fix

* Apply suggestions from code review

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* comment

* better error

* doc

* (add unsigned module 🤦)

* doc

* fix

* implement for node-template as well

* add validated unsigned to executor

* fix

* fix

* bump version

* testing xt

* remove extraneous logic

* licence

* impl test

substrate/srml/support/test/tests/final_keys.rs

@@ -1,3 +1,19 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate 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.
+
+// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
 use runtime_io::{with_externalities, Blake2Hasher};
 use srml_support::{StorageValue, StorageMap, StorageDoubleMap};
 use srml_support::storage::unhashed;