Merge branch 'master' into ethminer_crate

Conflicts:
	util/bigint/src/uint.rs

README.md

@@ -34,9 +34,6 @@ Then, download and build Parity:
 git clone https://github.com/ethcore/parity
 cd parity
 
-# parity should be built with rust beta
-multirust override beta
-
 # build in release mode
 cargo build --release
 ```

util/bigint/src/uint.rs

@@ -36,6 +36,7 @@
 //! The functions here are designed to be fast.
 //!
 
+#[cfg(all(asm_available, target_arch="x86_64"))]
 use std::mem;
 use std::fmt;
 use std::cmp;