docs(Http): add docs for Http lib

Fixes #2442

modules/angular2/http.ts

@@ -1,10 +1,41 @@
+/**
+ * @module
+ * @public
+ * @description
+ * The http module provides services to perform http requests. To get started, see the {@link Http}
+ * class.
+ */
 import {bind, Binding} from 'angular2/di';
 import {Http, HttpFactory} from './src/http/http';
-import {XHRBackend} from 'angular2/src/http/backends/xhr_backend';
+import {XHRBackend, XHRConnection} from 'angular2/src/http/backends/xhr_backend';
 import {BrowserXHR} from 'angular2/src/http/backends/browser_xhr';
-import {BaseRequestOptions} from 'angular2/src/http/base_request_options';
+import {BaseRequestOptions, RequestOptions} from 'angular2/src/http/base_request_options';
 
-export {Http};
+export {MockConnection, MockBackend} from 'angular2/src/http/backends/mock_backend';
+export {Request} from 'angular2/src/http/static_request';
+export {Response} from 'angular2/src/http/static_response';
+
+export {Http, XHRBackend, XHRConnection, BaseRequestOptions, RequestOptions, HttpFactory};
+export {IHttp} from 'angular2/src/http/interfaces';
+export {Headers} from 'angular2/src/http/headers';
+
+/**
+ * Provides a basic set of injectables to use the {@link Http} service in any application.
+ *
+ * #Example
+ *
+ * ```
+ * import {httpInjectables, Http} from 'angular2/http';
+ * @Component({selector: 'http-app', appInjector: [httpInjectables]})
+ * @View({template: '{{data}}'})
+ * class MyApp {
+ *   constructor(http:Http) {
+ *     http.request('data.txt').subscribe(res => this.data = res.text());
+ *   }
+ * }
+ * ```
+ *
+ */
 export var httpInjectables: List<any> = [
   bind(BrowserXHR)
       .toValue(BrowserXHR),