Add prettier & update eslint

Author: dozoisch

.eslintrc

@@ -0,0 +1,19 @@
+"use strict";
+module.exports = {
+  extends: ["eslint:recommended", "prettier", "prettier/react"],
+  parserOptions: {
+    sourceType: "module",
+    ecmaVersion: "2018",
+    ecmaFeatures: {
+      jsx: true,
+    },
+  },
+  env: {
+    es6: true,
+    browser: true,
+  },
+  plugins: ["prettier"],
+  rules: {
+    "prettier/prettier": "error",
+  },
+};

.eslintrc.js

@@ -0,0 +1,5 @@
+{
+  "printWidth": 100,
+  "trailingComma": "all",
+  "parser": "babylon"
+}

.prettierrc

@@ -1,3 +1,5 @@
+/* eslint-env node */
+"use strict";
 // For a detailed explanation regarding each configuration property, visit:
 // https://jestjs.io/docs/en/configuration.html
 
@@ -133,15 +135,10 @@ module.exports = {
   // testLocationInResults: false,
 
   // The glob patterns Jest uses to detect test files
-  testMatch: [
-    "**/?(*.)+(spec|test).js?(x)",
-  ],
+  testMatch: ["**/?(*.)+(spec|test).js?(x)"],
 
   // An array of regexp pattern strings that are matched against all test paths, matched tests are skipped
-  testPathIgnorePatterns: [
-    "/node_modules/",
-    "webpack.config.test.js",
-  ],
+  testPathIgnorePatterns: ["/node_modules/", "webpack.config.test.js"],
 
   // The regexp pattern Jest uses to detect test files
   // testRegex: "",