converts an RGB color code to the HSV format
| r | number | the Red color value |
| g | number | the Green color value |
| b | number | the Blue color value |
| array | an array with HUE SATURATION BRIGHTNESS values |
webix.color.rgbToHsv(115,116,133);
// -> [236.66666666666669, 0.13533834586466165, 0.5215686274509804]