* Generalize BlockImport
- move ImportBlock, BlockOrigin, ImportResult into shared sr-primitives
- let Consensus provide and traits again
- update consensus traits to latest development
- implement traits on client::Client, test_client::TestClient
- update RHD to use the new import_block API
* Move ImportBlock into consensus-common
* Send import notification in aura tests
* Integrating aura into service
* Make Signatures more generic
* Aura Block Production with the given key
* run aura on the thread pool
* start at exact step start in aura
* Add needed wasm blob, in leiu of better solutions.
* Make API ids consistent with traits and bring upstream for sharing.
* Add decrease_free_balance to Balances module
* Encode `Metadata` once instead of two times
* Bitops include xor
* Upgrade key module.
* Default pages to somewhat bigger.
* Introduce upgrade key into node
* Add `Created` event
Gav Wood