added canonical cbor map key sorting

[stoneburner]

this adds the ability to order the keys of a map according to the CBOR RFC: https://tools.ietf.org/html/rfc7049#section-3.9

its now its own function, maybe its ok to replace the default implementation?

(I noticed that many other CBOR library do this sorting i.e. https://github.com/c-rack/cbor-java/blob/master/src/main/java/co/nstant/in/cbor/encoder/MapEncoder.java#L46)