export amplitude type because amplitude-js is a UMD module

Without doing this, tsc complains that node_modules/@types/amplitude-js/index.d.ts is not a module

types/amplitude-js/amplitude-js-tests.ts

@@ -1,5 +1,7 @@
 // Tests for Amplitude SDK TypeScript definitions
 
+import amplitude = require('amplitude-js');
+
 module Amplitude.Tests {
 
     function all() {

types/amplitude-js/index.d.ts

@@ -4,7 +4,10 @@
 //                 Dan Manastireanu <https://github.com/danmana>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
-declare module amplitude {
+export = amplitude;
+export as namespace amplitude;
+
+declare namespace amplitude {
 
     type Callback = (responseCode: number, responseBody: string, details?: { reason: string; }) => void;
     type LogReturn = number | void;