fixed build issues with stabilized feature WrappingOps

src/evm/interpreter.rs

@@ -4,7 +4,6 @@ use common::*;
 use evm;
 use super::instructions as instructions;
 use super::instructions::Instruction;
-use std::num::wrapping::OverflowingOps;
 use std::marker::Copy;
 use evm::{MessageCallResult, ContractCreateResult};
 

src/lib.rs

@@ -1,6 +1,5 @@
 #![feature(cell_extras)]
 #![feature(augmented_assignments)]
-#![feature(wrapping)]
 //#![feature(plugin)]
 //#![plugin(interpolate_idents)]
 //! Ethcore's ethereum implementation