Update to unsplash (#938)

* Switch photos from 500px to Unsplash

* Good bye comment view :(

* Update license headers

examples/ASDKgram/Sample/PhotoFeedBaseController.h

@@ -1,20 +1,18 @@
 //
 //  PhotoFeedBaseController.h
-//  Sample
-//
-//  Created by Huy Nguyen on 20/12/16.
+//  Texture
 //
 //  Copyright (c) 2014-present, Facebook, Inc.  All rights reserved.
 //  This source code is licensed under the BSD-style license found in the
-//  LICENSE file in the root directory of this source tree. An additional grant
-//  of patent rights can be found in the PATENTS file in the same directory.
+//  LICENSE file in the /ASDK-Licenses directory of this source tree. An additional
+//  grant of patent rights can be found in the PATENTS file in the same directory.
 //
-//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-//  FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
-//  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-//  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//  Modifications to this file made after 4/13/2017 are: Copyright (c) through the present,
+//  Pinterest, Inc.  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
 //
 
 #import <AsyncDisplayKit/AsyncDisplayKit.h>
@@ -34,6 +32,5 @@
 #pragma mark - Subclasses must override these methods
 
 - (void)loadPage;
-- (void)requestCommentsForPhotos:(NSArray *)newPhotos;
 
 @end