Test the app on Android Emulator is not easy

[shanhuiyang]

We should skip the step to modify the default service host name.
Maybe we can use http://10.0.2.2?

[shanhuiyang]

Now by default you can test on Android emulator without change the default IP address.
But there still problem as opening debugging. Keep the issue opened.

[shanhuiyang]

Fixed the debug issue, found this ip does not work for Oauth2. Need further investigation.