新增 crud.js，整合通用的增删改查

src/assets/styles/sidebar.scss

@@ -13,7 +13,7 @@
     background-color: $menuBg;
     height: 100%;
     position: fixed;
-    font-size: 0px;
+    font-size: 0;
     top: 0;
     bottom: 0;
     left: 0;
@@ -30,7 +30,7 @@
     }
 
     .el-scrollbar__bar.is-vertical {
-      right: 0px;
+      right: 0;
     }
 
     .el-scrollbar {
@@ -146,7 +146,7 @@
   // mobile responsive
   .mobile {
     .main-container {
-      margin-left: 0px;
+      margin-left: 0;
     }
 
     .sidebar-container {