Upgrade to OkHttp3

Summary:
Update to [OkHttp](https://github.com/square/okhttp) to [OkHttp3](https://publicobject.com/2015/12/12/com-squareup-okhttp3/)

We must also update:
- Fresco to 0.10.0
- okio to 1.8.0

**Motivation**
Reasons for upgrading:
* Issue #4021
* "We discovered that RN Android sometimes fails to connect to the latest stable version of NGINX when HTTP/2 is enabled. We aren't seeing errors with other HTTP clients so we think it's specific to RN and OkHttp. Square has fixed several HTTP/2 bugs over the past eight months." - ide
* OkHttp3 will be maintained & improved, but OkHttp2 will only receive [security fixes](https://publicobject.com/2016/02/11/okhttp-certificate-pinning-vulnerability/)
* Cleaner APIs - "Get and Set prefixes are avoided"
* Deprecated/Removed - HttpURLConnection & Apache HTTP
* React Native apps are currently being forced to bundle two versions of OkHttp (v2 & v3), if another library uses v3
* Improved WebSocket performance - [CHANGELOG.md](https://github.com/square/okhttp/blob/master
Closes https://github.com/facebook/react-native/pull/6113

Reviewed By: andreicoman11, lexs

Differential Revision: D3292375

Pulled By: bestander

fbshipit-source-id: 7c7043eaa2ea63f95854108b401c4066098d67f7

ReactAndroid/src/main/java/com/facebook/react/common/BUCK

@@ -7,6 +7,7 @@ android_library(
     ':build_config',
     react_native_dep('third-party/java/infer-annotations:infer-annotations'),
     react_native_dep('third-party/java/jsr-305:jsr-305'),
+    react_native_dep('third-party/java/okhttp:okhttp3'),
   ],
   exported_deps = [
     react_native_dep('java/com/facebook/proguard/annotations:annotations'),

ReactAndroid/src/main/java/com/facebook/react/common/network/OkHttpCallUtil.java

@@ -0,0 +1,35 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ * <p/>
+ * 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.
+ */
+
+package com.facebook.react.common.network;
+
+import okhttp3.Call;
+import okhttp3.OkHttpClient;
+
+/**
+ * Helper class that provides the necessary methods for canceling queued and running OkHttp calls
+ */
+public class OkHttpCallUtil {
+
+  private OkHttpCallUtil() {
+  }
+
+  public static void cancelTag(OkHttpClient client, Object tag) {
+    for (Call call : client.dispatcher().queuedCalls()) {
+      if (tag.equals(call.request().tag())) {
+        call.cancel();
+      }
+    }
+    for (Call call : client.dispatcher().runningCalls()) {
+      if (tag.equals(call.request().tag())) {
+        call.cancel();
+      }
+    }
+  }
+}