Fix NPE in cancelling network calls

Summary:
Issue reported here
https://github.com/facebook/react-native/issues/7755#issuecomment-222950463

Converting int to Integer explicitly and not cancelling the call more than once
should fix it.

Reviewed By: bestander

Differential Revision: D3371238

fbshipit-source-id: cb00663b4ca19a788bd27b971b6447cc0788a818

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

@@ -24,11 +24,13 @@ public class OkHttpCallUtil {
     for (Call call : client.dispatcher().queuedCalls()) {
       if (tag.equals(call.request().tag())) {
         call.cancel();
+        return;
       }
     }
     for (Call call : client.dispatcher().runningCalls()) {
       if (tag.equals(call.request().tag())) {
         call.cancel();
+        return;
       }
     }
   }

ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkingModule.java

@@ -384,7 +384,7 @@ public final class NetworkingModule extends ReactContextBaseJavaModule {
     new GuardedAsyncTask<Void, Void>(getReactApplicationContext()) {
       @Override
       protected void doInBackgroundGuarded(Void... params) {
-        OkHttpCallUtil.cancelTag(mClient, requestId);
+        OkHttpCallUtil.cancelTag(mClient, Integer.valueOf(requestId));
       }
     }.execute();
   }