Add AJAX

[calebthewood]

There are two areas where AJAX would really benefit this site:

• When you like/unlike a warble, you shouldn’t have to refresh the page
• You should be able to compose a warble via a popup modal that is available on every page via the navigation bar button.

[calebthewood]

Ticket Resolved across multiple commits, no branches.

1. Resolved via handleBtns function in static/javascript/index.js
2. Resolved by creating modal in base.html and adding MessageForm to g