Base Value and Base Sum missing from the model

[drasko]

SenML struct here: https://github.com/cisco/senml/blob/master/senml.go#L33 is missing Base Value (bv) and Base Sum (bs) fields referenced in the spec: https://tools.ietf.org/html/draft-ietf-core-senml-10#page-9

[fluffy]

Thanks - I will have a look at fixing that.