message: [Improvement] Sku: add getSkuData method
diff: @@ -22,8 +22,8 @@ Vue.use(Sku);
  :reset-stepper-on-hide="resetStepperOnHide"
  :reset-selected-sku-on-hide="resetSelectedSkuOnHide"
  :disable-stepper-input="disableStepperInput"
  - @buy-clicked="handleBuyClicked"
  - @add-cart="handleAddCartClicked"
  + @buy-clicked="onBuyClicked"
  + @add-cart="onAddCartClicked"
  />
  ```
  @@ -42,15 +42,13 @@ Vue.use(Sku);
  :quota-used="quotaUsed"
  :reset-stepper-on-hide="true"
  :initial-sku="initialSku"
  - @buy-clicked="handleBuyClicked"
  - @add-cart="handleAddCartClicked"
  + @buy-clicked="onBuyClicked"
  + @add-cart="onAddCartClicked"
  >
  - <!-- hide sku messages -->
  - <template slot="sku-messages"></template>
  <!-- custom sku actions -->
  <template slot="sku-actions" slot-scope="props">
  <div class="van-sku-actions">
  - <van-button bottom-action @click="handlePointClicked">Button</van-button>
  + <van-button bottom-action @click="onPointClicked">Button</van-button>
  <!-- trigger sku inner event -->
  <van-button type="primary" bottom-action @click="props.skuEventBus.$emit('sku:buy')">Button</van-button>
  </div>
  @@ -82,6 +80,12 @@ Vue.use(Sku);
  | add-cart | Triggered when click cart button | data: Object |
  | buy-clicked | Triggered when click buy button | data: Object |
  +### Methods
  +
  +| Method | Description |
  +|-----------|-----------|
  +| getSkuData() | Get current sku data |
  +
  ### Slot
  | Name | Description |
  