Auto merge of #161 - cuviper:shifty-ints, r=hauleth
Auto merge of #161 - cuviper:shifty-ints, r=hauleth

Add signed/unsigned shifts to PrimInt

None

rust-num/num-traits,rust-num/num-integer,rust-num/num-integer,rust-num/num,rust-num/num-traits,DonSheddow/num,rust-num/num,rust-lang/num,DonSheddow/num,rust-num/num-bigint,koverstreet/num,rust-lang/num,koverstreet/num,vks/num,vks/num,rust-num/num-bigint