fix typo(#965)

src/components/Upload/singleImage.vue

 <template>
     <div class="upload-container">
         <el-upload class="image-uploader" :data="dataObj" drag :multiple="false" :show-file-list="false" action="https://httpbin.org/post"
-            :on-success="handleImageScucess">
+            :on-success="handleImageSuccess">
             <i class="el-icon-upload"></i>
             <div class="el-upload__text">将文件拖到此处，或<em>点击上传</em></div>
         </el-upload>
@@ -43,7 +43,7 @@ export default {
     emitInput(val) {
       this.$emit('input', val)
     },
-    handleImageScucess() {
+    handleImageSuccess() {
       this.emitInput(this.tempUrl)
     },
     beforeUpload() {

src/components/Upload/singleImage2.vue

 <template>
   <div class="singleImageUpload2 upload-container">
     <el-upload class="image-uploader" :data="dataObj" drag :multiple="false" :show-file-list="false" action="https://httpbin.org/post"
-      :on-success="handleImageScucess">
+      :on-success="handleImageSuccess">
       <i class="el-icon-upload"></i>
       <div class="el-upload__text">Drag或<em>点击上传</em></div>
     </el-upload>
@@ -42,7 +42,7 @@ export default {
     emitInput(val) {
       this.$emit('input', val)
     },
-    handleImageScucess() {
+    handleImageSuccess() {
       this.emitInput(this.tempUrl)
     },
     beforeUpload() {

src/components/Upload/singleImage3.vue

 <template>
   <div class="upload-container">
     <el-upload class="image-uploader" :data="dataObj" drag :multiple="false" :show-file-list="false" action="https://httpbin.org/post"
-      :on-success="handleImageScucess">
+      :on-success="handleImageSuccess">
       <i class="el-icon-upload"></i>
       <div class="el-upload__text">将文件拖到此处，或<em>点击上传</em></div>
     </el-upload>
@@ -50,7 +50,7 @@ export default {
     emitInput(val) {
       this.$emit('input', val)
     },
-    handleImageScucess(file) {
+    handleImageSuccess(file) {
       this.emitInput(file.files.file)
     },
     beforeUpload() {