Change error to warning to make action exporting more consistent

.eslintrc.json

@@ -43,7 +43,8 @@
         "react-native/no-inline-styles": 2,
         "react-native/no-color-literals": 2,
         "react/jsx-filename-extension": 0,
-        "react/prefer-stateless-function": 1
+        "react/prefer-stateless-function": 1,
+        "import/prefer-default-export": 1
     }
 
 }

app/actions/login.js

 import * as types from './actionTypes';
 
-export default function login(username, password) {
+export function login(username, password) {
   return {
     type: types.LOGIN,
     success: password === '42',