Bump version to v0.2.28
Bump version to v0.2.28

tempbottle/rust-crypto,tempbottle/rust-crypto,nmathewson/rust-crypto,PeterReid/rust-crypto,thinkingfish/rust-crypto,nmathewson/rust-crypto,mseri/rust-crypto,mseri/rust-crypto,thinkingfish/rust-crypto,canndrew/rust-crypto,DaGenix/rust-crypto,andreasots/rust-crypto,DaGenix/rust-crypto,andreasots/rust-crypto,canndrew/rust-crypto,PeterReid/rust-crypto