Moved simulation to front end and added additional country

[amy-lei]

• The function that previously calculated the number of supporters given a budget proposal is now moved to the frontend. Now, results due to changes in budget are reflected real-time.
• Rather than an alert button that alerts user from exceeding the budget, the component tracks the total and blocks user to sliding to such numbers.
• Added additional country information and allowed for user to change countries via a dropdown.