android: workaround for building

Somehow the bundle doesn't get included in the APK when I build this branch on
one laptop, but works on another, go figure. All of this has changed with the RN
0.59 update, so this is just a band-aid for 19.0 builds.

android/sdk/build.gradle

@@ -139,8 +139,8 @@ android.libraryVariants.all { def variant ->
         //
         if (currentBundleTask.enabled) {
             copy {
-                from(jsBundleDir)
-                into(assetsDir)
+                from(jsBundleFile)
+                into("${assetsDir}/")
             }
         }
     }