Allow to customize frame, feedback and oval colors

[jakubkoci]

This allows adding customization attributes as objects in opts JSON to be counterparts for SDK customization objects (frame, feedback, oval). I just added feedback and oval for now, but I can refactor the frame in the same way later.

Example of config:

{ 
  ...
  backgroundColor: '#D50032',
  borderColor: '#FFFFFF',
  feedbackCustomization: {
    backgroundColor: ['#D3284C', '#F05A78'],
  },
  ovalCustomization: {
    progressColor1: '#FA551E',
    progressColor2: '#D3284C',
  },
  ...
}

What do you think?