[License] Simplify the Texture license to be pure Apache 2 (removing ASDK-Licenses). (#1077)

* [License] Simplify the Texture license to be pure Apache 2 (removing ASDK-Licenses)

With permission of the Facebook Open Source team, we are simplifying the Texture
license so that clients can rely on the Apache 2 terms that most of Texture is
already covered by. This means that code originally forked from AsyncDisplayKit
will be re-licensed from "BSD 3-clause + PATENTS v2" to Apache 2 without a
PATENTS file.

After getting confirmation that the updates to these core files look good, we'll
propagate this new license header to all files (in this same PR) and get sign-off
from all parties before landing.

* [License] Update all Texture source files to be pure Apache 2.

* Changelog entry for Apache 2 license update.

* Revert "[License] Update all Texture source files to be pure Apache 2."

This reverts commit ffa0fbbba9717d871dd16c4b07539f2f8208fc2b.

* [License] Update all Texture source files to be pure Apache 2, maintaining copyrights.

* [License] Update CONTRIBUTING, README, Podspec & Dangerfile.

Source/Private/TextExperiment/Utility/NSAttributedString+ASText.h

@@ -1,12 +1,9 @@
 //
 //  NSAttributedString+ASText.h
-//  Modified from YYText <https://github.com/ibireme/YYText>
+//  Texture
 //
-//  Created by ibireme on 14/10/7.
-//  Copyright (c) 2015 ibireme.
-//
-//  This source code is licensed under the MIT-style license found in the
-//  LICENSE file in the root directory of this source tree.
+//  Copyright (c) Pinterest, Inc.  All rights reserved.
+//  Licensed under Apache 2.0: http://www.apache.org/licenses/LICENSE-2.0
 //
 
 #import <UIKit/UIKit.h>