android.system.ErrnoException on SntpClient

Using the `3.4` Rx version of the lib, with `initializeNtp` I get this error `android.system.ErrnoException sendto failed: EPERM (Operation not permitted)`. This happens with a lot of Android versions and device brands.

```
Caused by android.system.ErrnoException: sendto failed: EPERM (Operation not permitted)
at libcore.io.Linux.sendtoBytes(Linux.java)
at libcore.io.Linux.sendto(Linux.java:225)
at libcore.io.BlockGuardOs.sendto(BlockGuardOs.java:304)
at libcore.io.IoBridge.sendto(IoBridge.java:569)
at java.net.PlainDatagramSocketImpl.send(PlainDatagramSocketImpl.java:124)
at java.net.DatagramSocket.send(DatagramSocket.java:721)
at com.instacart.library.truetime.SntpClient.doubleMillis(SntpClient.java:10)
at com.instacart.library.truetime.SntpClient.requestTime(SntpClient.java:116)
at com.instacart.library.truetime.TrueTime.requestTime(TrueTime.java:133)
at com.instacart.library.truetime.TrueTimeRx$4$1$2.subscribe(TrueTimeRx.java:211)
at io.reactivex.internal.operators.flowable.FlowableCreate.subscribeActual(FlowableCreate.java:71)
at io.reactivex.Flowable.subscribe(Flowable.java:14805)
at io.reactivex.Flowable.subscribe(Flowable.java:14752)
at io.reactivex.internal.operators.flowable.FlowableSubscribeOn$SubscribeOnSubscriber.run(FlowableSubscribeOn.java:82)
at io.reactivex.internal.schedulers.ScheduledRunnable.run(ScheduledRunnable.java:66)
at io.reactivex.internal.schedulers.ScheduledRunnable.call(ScheduledRunnable.java:57)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:301)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
at java.lang.Thread.run(Thread.java:764)
```