Added Gutenberg Block

Added Gutenberg Block which allows users to preview, edit and render existing charts, with ability to create new charts in an upcoming release. It addresses: #282

Author: HardeepAsrani

classes/Visualizer/Gutenberg/.eslintrc

@@ -0,0 +1,36 @@
+{
+    "env": {
+        "browser": true,
+        "es6": true
+    },
+    "extends": "wordpress",
+    "parserOptions": {
+        "ecmaFeatures": {
+            "jsx": true
+        },
+        "ecmaVersion": 2018,
+        "sourceType": "module"
+    },
+    "plugins": [
+        "react"
+    ],
+    "rules": {
+        "indent": [
+            "error",
+            "tab"
+        ],
+        "linebreak-style": [
+            "error",
+            "unix"
+        ],
+        "quotes": [
+            "error",
+            "single"
+        ],
+        "semi": [
+            "error",
+            "always"
+        ],
+        "no-cond-assign": "off"
+    }
+}