Enable LeakCanary to test for Activity leaks.

sample/src/main/java/example/zxing/SampleApplication.java

@@ -0,0 +1,16 @@
+package example.zxing;
+
+import android.app.Application;
+
+import com.squareup.leakcanary.LeakCanary;
+
+/**
+ *
+ */
+public class SampleApplication extends Application {
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        LeakCanary.install(this);
+    }
+}