skillColor( lvl ) {
    const idx = _skillLevelToIndex(lvl);
    const skillColors = (this.theme && this.theme.palette &&
      this.theme.palette.skillLevels) ||
      [ '#FFFFFF', '#5CB85C', '#F1C40F', '#428BCA', '#C00000' ];
    return skillColors[idx];
  }
Convert a skill level to an RGB color triplet. TODO: refactor
  @method skillColor
  @param lvl Input skill level. Skill level can be expressed as a string
  ("beginner", "intermediate", etc.), as an integer (1,5,etc), as a string
  integer ("1", "5", etc.), or as an RRGGBB color triplet ('#C00000',
  '#FFFFAA').