fix: no-unused-expressions

```
/Users/1ambda/github/apache/apache-zeppelin/zeppelin-master/zeppelin-web/src/app/tabledata/transformation.js (1/0)
  ✖  21:5  Expected an assignment or function call and instead saw an expression  no-unused-expressions
```

zeppelin-web/.eslintrc

@@ -32,7 +32,6 @@
   },
   "rules": {
     "prefer-rest-params": 0,
-    "no-unused-expressions": 0,
     "prefer-spread": 0,
     "no-redeclare": 0,
     "no-var": 0,

zeppelin-web/src/app/notebook/paragraph/result/result.controller.js

@@ -103,16 +103,16 @@ function ResultCtrl ($scope, $rootScope, $route, $window, $routeParams, $locatio
   };
 
   // type
-  $scope.type;
+  $scope.type = null;
 
   // Data of the result
   var data;
 
   // config
-  $scope.config;
+  $scope.config = null;
 
   // resultId = paragraph.id + index
-  $scope.id;
+  $scope.id = null;
 
   // referece to paragraph
   var paragraph;
@@ -130,10 +130,10 @@ function ResultCtrl ($scope, $rootScope, $route, $window, $routeParams, $locatio
   var enableHelium = false;
 
   // graphMode
-  $scope.graphMode;
+  $scope.graphMode = null;
 
   // image data
-  $scope.imageData;
+  $scope.imageData = null;
 
   // queue for append output
   const textResultQueueForAppend = [];

zeppelin-web/src/app/tabledata/transformation.js

@@ -18,7 +18,7 @@
 export default class Transformation {
   constructor (config) {
     this.config = config;
-    this._emitter;
+    this._emitter = () => {};
   }
 
   /**

zeppelin-web/src/app/visualization/visualization.js

@@ -21,7 +21,7 @@ export default class Visualization {
     this.config = config;
     this._dirty = false;
     this._active = false;
-    this._emitter;
+    this._emitter = () => {};
   }
 
   /**