Update BeamLargeFiles/build.gradle to fix null output dir

The build.gradle file for BeamLargeFiles wasn't importing the
template engine dependencies, so it wasn't setting any of the
build variables that should've been set.

This was causing builds to get sent to a null directory, as well
as causing emitGradleZip to go into an infinite loop.

Change-Id: I640d67253003a450ed9b1e47243bc9ce08142b30
diff --git a/connectivity/nfc/BeamLargeFiles/build.gradle b/connectivity/nfc/BeamLargeFiles/build.gradle
index c7f6491..cca9ac3 100644
--- a/connectivity/nfc/BeamLargeFiles/build.gradle
+++ b/connectivity/nfc/BeamLargeFiles/build.gradle
@@ -1,8 +1,10 @@
-
 // BEGIN_EXCLUDE
-apply from: "../../../../../build/build.gradle"
+import com.example.android.samples.build.SampleGenPlugin
+apply plugin: SampleGenPlugin
+
 samplegen {
   pathToBuild "../../../../../build"
   pathToSamplesCommon "../../../common"
 }
+apply from: "../../../../../build/build.gradle"
 // END_EXCLUDE