Added sample app for testing jank using the leanback library.

Change-Id: If3a062a9a0d8461d3cb0b9fbab9611c271d8d8f6
diff --git a/settings.gradle b/settings.gradle
index dd64402..b217355 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -102,6 +102,9 @@
 include ':support-leanback-demos'
 project(':support-leanback-demos').projectDir = new File(samplesRoot, 'SupportLeanbackDemos')
 
+include ':support-leanback-jank'
+project(':support-leanback-jank').projectDir = new File(samplesRoot, 'SupportLeanbackJank')
+
 include ':support-percent-demos'
 project(':support-percent-demos').projectDir = new File(samplesRoot, 'SupportPercentDemos')