[beta] Backporting (#6352)

* Better check the created accounts before showing Startup Wizard

* Tweaked snapshot params

ethcore/src/engines/null_engine.rs

@@ -62,6 +62,6 @@ impl Engine for NullEngine {
 	}
 
 	fn snapshot_components(&self) -> Option<Box<::snapshot::SnapshotComponents>> {
-		Some(Box::new(::snapshot::PowSnapshot(10000)))
+		Some(Box::new(::snapshot::PowSnapshot::new(10000, 10000)))
 	}
 }