package rx.android.preferences does not exist

Hi.

I'm trying to do a test compile with some devices I've made, but I'm getting the following error:
C:\Users\Matheus\Desktop\device-frame-generator-master\app\src\main\java\com\f2prateek\dfg\DeviceProvider.java:36: error: package rx.android.preferences does not exist
import rx.android.preferences.StringPreference;

The same issua happens on another files, and every symbol class that's referred to it gives me an error because of that.

Is there a way to fix it on my end?