通过 gradle 引用 play-services 停止为我工作 - 归结为 - 甚至我最初用作参考的示例也停止工作： https:
//plus.google.com/+AndroidDevelopers/posts/4Yhpn6p9icf

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring project ':auth'.
> Failed to notify project evaluation listener.
   > Could not resolve all dependencies for configuration ':auth:compile'.
      > Could not find com.google.android.gms:play-services:3.1.36.
        Required by:
            gpsdemos:auth:unspecified

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

BUILD FAILED

Total time: 3.577 secs

我担心只是版本增加了，但这引发了两个问题：#1）什么是新版本？#2) 为什么旧版本不见了？