list

list 列表，用于将信息以列表的结构显示在页面上

目前列表项有普通，头像，圆头像，左缩略图和右缩略图几种展示方式，list下由列表项wa-item和它的子容器组成

可以嵌入图标再左侧或右侧

<view class="wa-list">
    <view class="wa-item">
      item
    </view>
    <view class="space"></view>
    <view class="wa-item">
      <text class="icon-left ion-home"></text>
      item
    </view>
    <view class="wa-item">
      <text class="icon-right ion-chevron-right"></text>
      item
    </view>
    <view class="wa-item wa-item-ava">
      <text class="icon-right ion-chevron-right"></text>
      <image class="item-img" src="/image/user.jpg"></image>
      item-ava
    </view>
    <view class="wa-item wa-item-ava">
      <image class="item-img-round" src="/image/user.jpg"></image>
      item-ava
    </view>
    <view class="wa-item wa-item-thumbnail-left">
      <text class="icon-right ion-chevron-right"></text>
      <image class="item-img" src="/image/user.jpg"></image>
      item-thumbnail-left
    </view>
    <view class="wa-item wa-item-thumbnail-right">
      <image class="item-img" src="/image/user.jpg"></image>
      item-thumbnail-right
    </view>
    <view class="space">space</view>
</view>