Update dependencies

- add eslint
- update dependencies purgecss, ...

Author: Ffloriel

packages/rollup-plugin-purgecss/.eslintrc

@@ -0,0 +1,13 @@
+{
+    "extends": "eslint:recommended",
+    "parserOptions": {
+        "ecmaVersion": 6,
+        "sourceType": "module"
+    },
+    "env": {
+        "browser": true,
+        "commonjs": true,
+        "node": true,
+        "es6": true
+    }
+}