Convert HSV object to string

[Bjarne Fyrstenborg]

I noticed the API has

toHex(), toRgb(), toHsl() and to toHsv().

Furthermore:

toHRgbString() and toHslString(), but why no toHsvString() function?

I guess it has been forgotten to add it here?
https://github.com/omgovich/colord/tree/master/src/colorModels