Rewards and slashing, early-exit of bad sessions (#234)

* Recompile runtime.

* Introduce and enforce block time

* Introduce early session ending.

* Report most of staking module

* rewards, proper early exit and slashing

* Fix build & session logic, introduce tests

* Fixed staking tests.

* Initial test for reward

* Fix test

* Tests for slashing

* Update/fix preset configs

* Fix some tests.

* Fix some staking tests

* Minor fix

* minor cleanups

* Fix build

* Rename timestamp::Value -> Moment

* Require final block of session to be timely

polkadot/runtime/wasm/Cargo.lock

@@ -905,6 +905,7 @@ dependencies = [
  "substrate-runtime-std 0.1.0",
  "substrate-runtime-support 0.1.0",
  "substrate-runtime-system 0.1.0",
+ "substrate-runtime-timestamp 0.1.0",
 ]
 
 [[package]]
@@ -927,6 +928,7 @@ dependencies = [
  "substrate-runtime-std 0.1.0",
  "substrate-runtime-support 0.1.0",
  "substrate-runtime-system 0.1.0",
+ "substrate-runtime-timestamp 0.1.0",
 ]
 
 [[package]]
@@ -977,6 +979,7 @@ dependencies = [
  "serde_derive 1.0.64 (registry+https://github.com/rust-lang/crates.io-index)",
  "substrate-codec 0.1.0",
  "substrate-primitives 0.1.0",
+ "substrate-runtime-consensus 0.1.0",
  "substrate-runtime-io 0.1.0",
  "substrate-runtime-primitives 0.1.0",
  "substrate-runtime-std 0.1.0",