Update playground dependencies

Author: MadLittleMods

.eslintrc

@@ -0,0 +1,108 @@
+{
+	"env": {
+		"browser": true,
+	},
+	"parserOptions": {
+		"ecmaVersion": 6,
+		"sourceType": "script"
+	},
+	"extends": "eslint:recommended",
+	"rules": {
+		"indent": "off",
+		"comma-dangle": "off",
+		"quotes": "off",
+		"eqeqeq": [
+			"warn",
+			"allow-null"
+		],
+		"strict": [
+			"error",
+			"safe"
+		],
+		"no-unused-vars": [
+			"warn"
+		],
+		"no-extra-boolean-cast": [
+			"warn"
+		],
+		"complexity": [
+			"error",
+			{
+				"max": 12
+			}
+		],
+		"max-statements-per-line": [
+			"error",
+			{
+				"max": 3
+			}
+		],
+		"no-debugger": "error",
+		"no-dupe-keys": "error",
+		"no-unsafe-finally": "error",
+		"no-with": "error",
+		"no-useless-call": "error",
+		"no-spaced-func": "error",
+		"no-useless-escape": "warn",
+		"max-statements": [
+			"warn",
+			30
+		],
+		"max-depth": [
+			"error",
+			4
+		],
+		"no-throw-literal": [
+			"error"
+		],
+		"no-sequences": "error",
+		"no-warning-comments": [
+			"warn",
+			{
+				"terms": [
+					"fixme",
+					"xxx"
+				],
+				"location": "anywhere"
+			}
+		],
+		"radix": "error",
+		"yoda": "error",
+		"no-nested-ternary": "warn",
+		"no-whitespace-before-property": "error",
+		"no-trailing-spaces": ["error"],
+		"space-in-parens": [
+			"warn",
+			"never"
+		],
+		"max-nested-callbacks": [
+			"error",
+			6
+		],
+		"eol-last": "warn",
+		"no-mixed-spaces-and-tabs": "error",
+		"no-negated-condition": "warn",
+		"no-unneeded-ternary": "error",
+		"no-multi-spaces": [
+			"warn",
+			{
+				"exceptions": {
+					"Property": true
+				}
+			}
+		],
+		"key-spacing": [
+			"warn",
+			{
+				"singleLine": {
+					"beforeColon": false,
+					"afterColon": true
+				},
+				"multiLine": {
+					"beforeColon": false,
+					"afterColon": true,
+					"mode": "minimum"
+				}
+			}
+		],
+}

playground/.jshintrc

@@ -0,0 +1 @@
+package-lock=false

playground/.npmrc

@@ -6,12 +6,6 @@ The code playground for `postcss-css-variables` is [available live here](https:/
 
 # Build
 
-## Prerequisites
-
- - [io.js](https://iojs.org/en/index.html) *or Node.js with support for template strings (not currently available)*
-
- ## Instructions:
-
 Run once to set everything up:
 
 `npm install`