Revert and redo #952 (#1133)

* Revert "Pruning changes trie without digests (#952)"

This reverts commit 6f9a505fba.

* pruning changes tries without digests

* u64::max_value()

* Update wasm files and fix merge conflict

* Fixes tests

substrate/srml/example/src/lib.rs

@@ -313,6 +313,7 @@ mod tests {
 		t.extend(GenesisConfig::<Test>{
 			dummy: 42,
 			foo: 24,
+			_genesis_phantom_data: Default::default(),
 		}.build_storage().unwrap().0);
 		t.into()
 	}