fix(Grid): 修复组件 lintap 事件不会触发问题

修复 Grid 组件 lintap 事件以及 tapGridItem 事件不会触发问题

close #1059

Author: murongg

src/grid/index.wxml

@@ -1,6 +1,6 @@
-<view class="l-grid l-class" mut-bind:tap="tapGrid">
+<view class="l-grid l-class" bind:tap="tapGrid">
     <view 
-        mut-bind:tap="tapGridItem"
+        bind:tap="tapGridItem"
         data-grid-index="{{item.index}}"
         class="l-grid-item l-class-grid l-grid-class {{index%rowNum !== rowNum-1 &&(showBorder||showColBorder) ? 'side-grid':''}} {{(index<gridItems.length-(gridItems.length%rowNum||rowNum)) &&(showBorder||showRowBorder)? 'center-grid':''}}" wx:for="{{gridItems}}" wx:key="key"
         style="min-width:{{100/rowNum}}%;"