Clean up CLI interface (#3334)

* Clean up CLI interface

- Removes `--validator` and `--grandpa-voter`
- Make `--alice` etc work without `--dev`

* Style fixes

substrate/core/service/test/src/lib.rs

@@ -190,7 +190,6 @@ fn node_config<F: ServiceFactory> (
 		offchain_worker: false,
 		force_authoring: false,
 		disable_grandpa: false,
-		grandpa_voter: false,
 		dev_key_seed: key_seed,
 	}
 }