Change Debug impl to local Client

In preparation for adding another async client change the Debug impl to
refer to the local sync Client so that there is no conflict when adding
the second async Client struct.

Author: jamillambert

jsonrpc/src/client.rs

@@ -124,7 +124,7 @@ impl Client {
     }
 }
 
-impl fmt::Debug for crate::Client {
+impl fmt::Debug for Client {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "jsonrpc::Client(")?;
         self.transport.fmt_target(f)?;