修改checkbox支持

src/components/Checkbox.vue

 <template>
-  <el-checkbox v-model="model" v-bind="$attrs" v-on="$listeners" v-bind:disabled="isDisable">
+  <el-checkbox v-model="model" :true-label="trueLabel" :false-label="falseLabel" v-bind="$attrs" v-on="$listeners" v-bind:disabled="isDisable">
     <slot></slot>
   </el-checkbox>
 </template>
@@ -14,18 +14,23 @@ export default {
     disabled: {
       type: Boolean,
       default: false
+    },
+    "true-label":{
+      type:String,
+      default:"X"
+    },
+    "false-label":{
+      type:String,
+      default:""
     }
   },
   computed: {
     model: {
       get () {
-        if(this.value)
-          return true
-        else 
-          return false
+        return this.value
       },
       set (newVal) {
-        this.$emit('input', newVal?"X":"")
+        this.$emit('input', newVal)
       }
     },
     mode () {