Change Annotatable to &Annotatable for nightly
Change Annotatable to &Annotatable for nightly

See: rust-lang/rust#25683

rust-num/num-traits,Emerentius/num,koverstreet/num,bluss/num,jbcrail/num,vks/num,rust-num/num-bigint,anchovieshat/num,achanda/num,rust-num/num,DonSheddow/num,rust-num/num,DonSheddow/num,rust-lang/num,anchovieshat/num,huonw/num,rust-num/num-bigint,koverstreet/num,ollie27/rust_num,vks/num,achanda/num,Ticki/num,hauleth/num,Gustorn/num,rust-num/num-integer,jdm/num,rust-num/num-integer,jbcrail/num,rust-lang/num,rust-num/num-traits