updated lib to require RN 0.57 minimum

updated testApp to latest RN
updated Fetch to version 3.0.3

Author: Elad Gil

testApp/ios/testAppTests/testAppTests.m

@@ -1,5 +1,5 @@
 /**
- * Copyright (c) 2015-present, Facebook, Inc.
+ * 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.
@@ -14,11 +14,11 @@
 #define TIMEOUT_SECONDS 600
 #define TEXT_TO_LOOK_FOR @"Welcome to React Native!"
 
-@interface testAppTests : XCTestCase
+@interface testApp2Tests : XCTestCase
 
 @end
 
-@implementation testAppTests
+@implementation testApp2Tests
 
 - (BOOL)findSubviewInView:(UIView *)view matching:(BOOL(^)(UIView *view))test
 {