Summary:
Update several files to use the proper copyright header:
```
// Copyright (c) Facebook, Inc. and its affiliates.
//
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.
```
In the case of Xcode project files, I used the shortform version, `Copyright (c) Facebook, Inc. and its affiliates.`
Reviewed By: axe-fb
Differential Revision: D10114529
fbshipit-source-id: a1f2d5a46d04797c1cf281ea9ab80d3a2caa6fb4