Fix build: ResponseBody not imported in OkHttpPendingResult

[apjanke]

Looks like #368 broke the build: in the current version, ResponseBody is used but not imported.

When I build from master at commit 6daaa17, I get this build error:

$ ./gradlew build

> Task :compileJava
warning: [options] bootstrap class path not set in conjunction with -source 1.7
/Users/janke/local/repos/google-maps-services-java/build/filtered/src/main/java/com/google/maps/internal/OkHttpPendingResult.java:224: error: cannot find symbol
    try (ResponseBody body = response.body()) {
         ^
  symbol:   class ResponseBody
  location: class OkHttpPendingResult<T,R>
  where T,R are type-variables:
    T extends Object declared in class OkHttpPendingResult
    R extends ApiResponse<T> declared in class OkHttpPendingResult
1 error


FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':compileJava'.
> Compilation failed; see the compiler error output for details.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

* Get more help at https://help.gradle.org

BUILD FAILED in 0s
2 actionable tasks: 2 executed

This PR fixes it by adding the import.

This PR also includes a style fix so the build passes the googleJavaFormat style check.

[apjanke]

Never mind. This was fixed by #370 while I was preparing this PR.

[domesticmouse]

Thanks! =)