removed util::common

ethcore/src/tests/client.rs

@@ -15,6 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use std::str::FromStr;
+use std::sync::Arc;
 use io::IoChannel;
 use client::{BlockChainClient, MiningBlockChainClient, Client, ClientConfig, BlockId};
 use state::{self, State, CleanupMode};