Fix eslint errors following upgrade

Author: iansinnott

.eslintrc

@@ -1,6 +1,8 @@
 {
   "extends": "airbnb/base",
   "rules": {
+    "lines-around-directive": [0],
+    "arrow-parens": [0],
     "no-param-reassign": [0],
     "max-len": [0],
     "prefer-arrow-callback": [0],

index.js

@@ -1,6 +1,4 @@
 /* eslint-disable vars-on-top, no-var, prefer-template */
-'use strict';
-
 var isRegExp = require('lodash.isregexp');
 var escapeRegExp = require('lodash.escaperegexp');
 var isString = require('lodash.isstring');

test.js

@@ -1,3 +1,4 @@
+/* eslint-disable import/no-extraneous-dependencies */
 import test from 'ava';
 import replaceString from './';