refactor(xhr): move render's xhr implementation to render/

The existence of this module in the services/ folder led some to believe xhr
is meant to be a general-purpose http library.

Fixes #2305

modules/angular2/test/render/dom/compiler/template_loader_spec.ts

@@ -16,7 +16,7 @@ import {UrlResolver} from 'angular2/src/services/url_resolver';
 
 import {ViewDefinition} from 'angular2/src/render/api';
 import {PromiseWrapper} from 'angular2/src/facade/async';
-import {MockXHR} from 'angular2/src/mock/xhr_mock';
+import {MockXHR} from 'angular2/src/render/xhr_mock';
 
 export function main() {
   describe('TemplateLoader', () => {

modules/angular2/test/render/dom/shadow_dom/emulated_scoped_shadow_dom_strategy_spec.ts

@@ -18,7 +18,7 @@ import {DOM} from 'angular2/src/dom/dom_adapter';
 import {Map, MapWrapper} from 'angular2/src/facade/collection';
 import {PromiseWrapper, Promise} from 'angular2/src/facade/async';
 
-import {XHR} from 'angular2/src/services/xhr';
+import {XHR} from 'angular2/src/render/xhr';
 
 import {
   EmulatedScopedShadowDomStrategy,

modules/angular2/test/render/dom/shadow_dom/style_inliner_spec.ts

@@ -17,7 +17,7 @@ import {isBlank} from 'angular2/src/facade/lang';
 import {Promise, PromiseWrapper} from 'angular2/src/facade/async';
 import {Map, MapWrapper} from 'angular2/src/facade/collection';
 
-import {XHR} from 'angular2/src/services/xhr';
+import {XHR} from 'angular2/src/render/xhr';
 
 import {bind} from 'angular2/di';
 

modules/angular2/test/render/xhr_impl_spec.ts

@@ -10,7 +10,7 @@ import {
   xit
 } from 'angular2/test_lib';
 
-import {XHRImpl} from 'angular2/src/services/xhr_impl';
+import {XHRImpl} from 'angular2/src/render/xhr_impl';
 import {PromiseWrapper} from 'angular2/src/facade/async';
 
 export function main() {

modules/angular2/test/render/xhr_mock_spec.ts

@@ -10,7 +10,7 @@ import {
   IS_DARTIUM,
   it,
 } from 'angular2/test_lib';
-import {MockXHR} from 'angular2/src/mock/xhr_mock';
+import {MockXHR} from 'angular2/src/render/xhr_mock';
 import {PromiseWrapper, Promise} from 'angular2/src/facade/async';
 import {isPresent} from 'angular2/src/facade/lang';