message: modify picker example
diff: <div class="wheel-wrapper" ref="wheelWrapper">
  <div class="wheel" v-for="data in pickerData">
  <ul class="wheel-scroll">
  - <li v-for="item in data" :class="{'disabled':item.disabled}" class="wheel-item">{{item.text}}</li>
  + <li v-for="item in data" :class="{'wheel-disabled-item':item.disabled}" class="wheel-item">{{item.text}}</li>
  </ul>
  </div>
  </div>
  overflow: hidden
  white-space: nowrap
  color: $color-dark-grey
  - &.disabled
  + &.wheel-disabled-item
  opacity: .2;
  .picker-footer
  height: 20px
  