Adder collator improvements (#1896)

* Fixes bug that collator wasn't sending `Declare` message

* Set authority discovery config

* Fixes bug that collator wasn't sending `Declare` message

* Adds real overseer feature and makes the wasm_validation fail with a
proper error

* Adds README

* Remove debug stuff

* Add feature

* Make adder collator use the correct parent when building a new block

polkadot/cli/src/command.rs

@@ -148,6 +148,7 @@ pub fn run() -> Result<()> {
 						config,
 						service::IsCollator::No,
 						grandpa_pause,
+						None,
 					).map(|full| full.task_manager),
 				}
 			})