fix(extension): fix another missed case sensitivity problem

Author: Alex Van Camp

extension/index.js

@@ -3,7 +3,7 @@
 const server = require('../../../lib/server');
 const clone = require('clone');
 const Subscription = require('./classes/subscription');
-const Tip = require('./classes/Tip');
+const Tip = require('./classes/tip');
 const EventEmitter = require('events');
 const emitter = new EventEmitter();