GeoApiContext should clean up working threads on exit.

Hello guys, I had a problem while doing a **PlacesApi.placeAutocomplete** request
I really don't know if that is a issue caused by the API or on our implementation.

We are developing an application that uses:
* Spring Boot `1.3.6.RELEASE`
* `Undertow`
* `com.google.maps:google-maps-services:0.1.17`

```
# application.properties
server.undertow.worker-threads=1000
server.undertow.io-threads=100
```

```
# EC2 AWS
m4.xlarge
```

```Dockerfile
# Dockerfile

FROM java:8
RUN apt-get update && apt-get install -y

WORKDIR /app
VOLUME /root/.gradle

COPY gradle/ /app/gradle/
COPY gradlew /app/gradlew
COPY build.gradle /app/build.gradle
COPY src/ /app/src/

COPY docker-entrypoint.sh /
ENTRYPOINT ["/docker-entrypoint.sh"]

CMD ["java","-jar","/app/build/libs/application-1.0.0.jar"]
```

```sh
# docker-entrypoint.sh

#!/bin/bash
set -e
./gradlew build -x test
exec "$@"
```

```java
@Service
public class GoogleMapsAPIService {
public List placeAutoComplete(String input, Double latitude, Double longitude, String language) {
GeoApiContext context = new GeoApiContext().setApiKey(GOOGLEMAPS_KEY);
LatLng location = new LatLng(latitude, longitude); // -23.52488881961586,-46.67578987777233

AutocompletePrediction[] autocompletePredictions = PlacesApi.placeAutocomplete(context, input)
.location(location)
.language("pt-BR")
.radius(1000)
.awaitIgnoreError();

return assemblyPrediction(autocompletePredictions);
}

private List assemblyPrediction(AutocompletePrediction[] autoCompletePredictions) {
List predictions = new ArrayList<>();

for (AutocompletePrediction autocompletePrediction : autoCompletePredictions) {
String placeId = autocompletePrediction.placeId;
String title = autocompletePrediction.terms[0].value;
String subTitle = Arrays.stream(autocompletePrediction.terms).skip(1).map(term -> term.value).collect(Collectors.joining(", "));

predictions.add(new Prediction(placeId, title, subTitle));
}

return predictions;
}
}
```

## **Sometimes we get this exception:**

```
2017-04-19 19:11:03,290 [XNIO-3 task-914] DEBUG org.springframework.web.servlet.DispatcherServlet - Last-Modified value for [/predictions] is: -1
2017-04-19 19:11:03,290 [XNIO-3 task-914] INFO com.application.services.GoogleMapsAPIService - GoogleMapsAPIService.placeAutoComplete
2017-04-19 19:11:03,290 [XNIO-3 task-914] DEBUG com.application.services.GoogleMapsAPIService - > Passenger: [7459]
2017-04-19 19:11:03,291 [XNIO-3 task-914] DEBUG com.application.services.GoogleMapsAPIService - > Input: [Alameda santos 2081]
2017-04-19 19:11:03,291 [XNIO-3 task-914] DEBUG com.application.services.GoogleMapsAPIService - > Latitude: [-23.52488881961586]
2017-04-19 19:11:03,291 [XNIO-3 task-914] DEBUG com.application.services.GoogleMapsAPIService - > Longitude: [-46.67578987777233]
2017-04-19 19:11:03,291 [XNIO-3 task-914] DEBUG com.application.services.GoogleMapsAPIService - > Language: [pt-BR]
2017-04-19 19:11:03,291 [XNIO-3 task-914] DEBUG com.application.services.GoogleMapsAPIService - > Radius: [1000]
2017-04-19 19:11:03,291 [XNIO-3 task-914] DEBUG org.springframework.web.servlet.DispatcherServlet - Could not complete request
org.springframework.web.util.NestedServletException: Handler processing failed; nested exception is java.lang.OutOfMemoryError: unable to create new native thread
at org.springframework.web.servlet.DispatcherServlet.triggerAfterCompletionWithError(DispatcherServlet.java:1305)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:979)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:858)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129)
at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:281)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)

Caused by: java.lang.OutOfMemoryError: unable to create new native thread
at java.lang.Thread.start0(Native Method)
at java.lang.Thread.start(Thread.java:714)
at com.google.maps.internal.RateLimitExecutorService.(RateLimitExecutorService.java:63)
at com.google.maps.OkHttpRequestHandler.(OkHttpRequestHandler.java:49)
at com.google.maps.GeoApiContext.(GeoApiContext.java:88)
at com.application.services.GoogleMapsAPIService.placeAutoComplete(GoogleMapsAPIService.java:175)
at com.application.controllers.PredictionsController.predictions(PredictionsController.java:31)
```

Stacktrace:
[stacktrace.txt](https://github.com/googlemaps/google-maps-services-java/files/939432/stacktrace.txt)

Do you know what could causes that?