Update to Substrate monthly-2021-12 (#22)

* Updates from the node template (up to rev. #1ea0883)

* Updates from the node template (up to rev. #1ea0883)

* Update to monthly-2021-11 - wip

* Update to monthly-2021-11-1 / rust 2021

* Cleanup

* Fix clippy warning

* use double quotes instead of single quotes

* Update node-template construct_runtime! syntax

* Fix incorrect validator set config; update runtime config & benchmarks

* Update to Substrate monthly-2021-12