Clean up sr-io (#3609)

* Move trait `Printable` into `sr-primitives`

* Cleanup runtime io trie_root interfaces

* Remove last generic bits from sr-io interface

* Fix srml-sudo after master merge

* Fix benchmarks

* Runtime bump

substrate/srml/example/src/lib.rs

@@ -579,7 +579,7 @@ impl<T: Trait + Send + Sync> SignedExtension for WatchDummy<T> {
 		// check for `set_dummy`
 		match call {
 			Call::set_dummy(..) => {
-				runtime_io::print("set_dummy was received.");
+				sr_primitives::print("set_dummy was received.");
 
 				let mut valid_tx = ValidTransaction::default();
 				valid_tx.priority = Bounded::max_value();