A view for prior months' expenses

Our view for the previous months' expenses should be one that renders a list of the existing months in our budget. It should give us the month, the budget allocated for the month, and have the years separated by some sort of a header. Then, on tap, it should go to the summary for each month to show us our previous months' expenses that were input.

We should create some functions in a new utilities file, named mockDataMethods, to help us mock the data for the previous months and populate our app:

// Expenses/app/utils/mockDataMethods.js 

import { setAsyncStorage } from './storageMethods'; 

const years = ['2017', '2016', '2015']; 
const months = ['1', '2', '3', '4', '5', '6', '7', '8', '9', '10', '11', '12']; 

const expenses = [ 
  { amount: '4', category: 'coffee', description: 'Latte' }, 
  { amount: '1.50', category: 'books', description: 'Sunday Paper' }, 
  { amount: '35', category: 'car', description: 'Gas' }, 
  { amount: '60', category: 'restaurant...