airbnb eslint config compatibility with vuex (vuejs-templates#1003)

Author: anubhav7495

template/.eslintrc.js

@@ -42,6 +42,22 @@ module.exports = {
       js: 'never',
       vue: 'never'
     }],
+    // disallow reassignment of function parameters
+    // disallow parameter object manipulation except for specific exclusions
+    'no-param-reassign': ['error', {
+      props: true,
+      ignorePropertyModificationsFor: [
+        'state', // for vuex state
+        'acc', // for reduce accumulators
+        'e', // for e.returnvalue
+        'ctx', // for Koa routing
+        'req', // for Express requests
+        'request', // for Express requests
+        'res', // for Express responses
+        'response', // for Express responses
+        '$scope', // for Angular 1 scopes
+      ]
+    }],
     // allow optionalDependencies
     'import/no-extraneous-dependencies': ['error', {
       optionalDependencies: ['test/unit/index.js']