Fix multiple issues when trying to import this module

* When you tried to require this module in a browserify bundle, it tried to
follow the require() calls inside dist/tus.js and then threw 'not found'
errors. The solution was to rename the require() function using the derequire
utility.

* Another issue occured when you wanted to import this module into a module
using the new ES importing sytanx in conjunction with Babel.

dist/tus.js

@@ -1,4 +1,4 @@
-(function(f){if(typeof exports==="object"&&typeof module!=="undefined"){module.exports=f()}else if(typeof define==="function"&&define.amd){define([],f)}else{var g;if(typeof window!=="undefined"){g=window}else if(typeof global!=="undefined"){g=global}else if(typeof self!=="undefined"){g=self}else{g=this}g.tus = f()}})(function(){var define,module,exports;return (function e(t,n,r){function s(o,u){if(!n[o]){if(!t[o]){var a=typeof require=="function"&&require;if(!u&&a)return a(o,!0);if(i)return i(o,!0);var f=new Error("Cannot find module '"+o+"'");throw f.code="MODULE_NOT_FOUND",f}var l=n[o]={exports:{}};t[o][0].call(l.exports,function(e){var n=t[o][1][e];return s(n?n:e)},l,l.exports,e,t,n,r)}return n[o].exports}var i=typeof require=="function"&&require;for(var o=0;o<r.length;o++)s(r[o]);return s})({1:[function(require,module,exports){
+(function(f){if(typeof exports==="object"&&typeof module!=="undefined"){module.exports=f()}else if(typeof define==="function"&&define.amd){define([],f)}else{var g;if(typeof window!=="undefined"){g=window}else if(typeof global!=="undefined"){g=global}else if(typeof self!=="undefined"){g=self}else{g=this}g.tus = f()}})(function(){var define,module,exports;return (function e(t,n,r){function s(o,u){if(!n[o]){if(!t[o]){var a=typeof require=="function"&&require;if(!u&&a)return a(o,!0);if(i)return i(o,!0);var f=new Error("Cannot find module '"+o+"'");throw f.code="MODULE_NOT_FOUND",f}var l=n[o]={exports:{}};t[o][0].call(l.exports,function(e){var n=t[o][1][e];return s(n?n:e)},l,l.exports,e,t,n,r)}return n[o].exports}var i=typeof require=="function"&&require;for(var o=0;o<r.length;o++)s(r[o]);return s})({1:[function(_dereq_,module,exports){
 "use strict";
 
 Object.defineProperty(exports, "__esModule", {
@@ -15,15 +15,10 @@ function fingerprint(file) {
   return ["tus", file.name, file.type, file.size, file.lastModified].join("-");
 }
 
-},{}],2:[function(require,module,exports){
+},{}],2:[function(_dereq_,module,exports){
 "use strict";
 
-Object.defineProperty(exports, "__esModule", {
-  value: true
-});
-exports.defaultOptions = exports.isSupported = exports.Upload = undefined;
-
-var _upload = require("./upload");
+var _upload = _dereq_("./upload");
 
 var _upload2 = _interopRequireDefault(_upload);
 
@@ -38,11 +33,16 @@ var Blob = _window.Blob;
 
 var isSupported = XMLHttpRequest && localStorage && Blob && typeof Blob.prototype.slice === "function";
 
-exports.Upload = _upload2.default;
-exports.isSupported = isSupported;
-exports.defaultOptions = defaultOptions;
+// The usage of the commonjs exporting syntax instead of the new ECMAScript
+// one is actually inteded and prevents weird behaviour if we are trying to
+// import this module in another module using Babel.
+module.exports = {
+  Upload: _upload2.default,
+  isSupported: isSupported,
+  defaultOptions: defaultOptions
+};
 
-},{"./upload":3}],3:[function(require,module,exports){
+},{"./upload":3}],3:[function(_dereq_,module,exports){
 "use strict";
 
 var _createClass = (function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; })(); /* global window, XMLHttpRequest */
@@ -51,11 +51,11 @@ Object.defineProperty(exports, "__esModule", {
   value: true
 });
 
-var _fingerprint = require("./fingerprint");
+var _fingerprint = _dereq_("./fingerprint");
 
 var _fingerprint2 = _interopRequireDefault(_fingerprint);
 
-var _extend = require("extend");
+var _extend = _dereq_("extend");
 
 var _extend2 = _interopRequireDefault(_extend);
 
@@ -421,7 +421,7 @@ Upload.defaultOptions = defaultOptions;
 
 exports.default = Upload;
 
-},{"./fingerprint":1,"extend":4}],4:[function(require,module,exports){
+},{"./fingerprint":1,"extend":4}],4:[function(_dereq_,module,exports){
 'use strict';
 
 var hasOwn = Object.prototype.hasOwnProperty;