Add WatchFace sample to master build.gradle

Change-Id: If0e578477145697f10b18ace5b0e420b68569b12
diff --git a/build.gradle b/build.gradle
index 740e531..789ffce 100644
--- a/build.gradle
+++ b/build.gradle
@@ -90,7 +90,8 @@
 "wearable/wear/SpeedTracker",
 "wearable/wear/SynchronizedNotifications",
 "wearable/wear/Timer",
-"wearable/wear/WatchViewStub"
+"wearable/wear/WatchViewStub",
+"wearable/wear/WatchFace",
 ]
 
 List<String> taskNames = [