updater_sample: update ui and README, clean-up

- ui: add text view for latest completion (error) code
- update README.md
- update MainActivity.java
- remove AbNonStreamingUpdate

Test: mmma bootable/recovery/updater_sample
Change-Id: Ie9bb64211c57d536036b04f13896e4937c392b6e
Signed-off-by: Zhomart Mukhamejanov <zhomart@google.com>
diff --git a/updater_sample/tests/src/com/example/android/systemupdatersample/util/FileDownloaderTest.java b/updater_sample/tests/src/com/example/android/systemupdatersample/util/FileDownloaderTest.java
index dc7ec09..80506ee 100644
--- a/updater_sample/tests/src/com/example/android/systemupdatersample/util/FileDownloaderTest.java
+++ b/updater_sample/tests/src/com/example/android/systemupdatersample/util/FileDownloaderTest.java
@@ -60,7 +60,7 @@
         File packageFile = Paths
                 .get(mTargetContext.getCacheDir().getAbsolutePath(), "ota.zip")
                 .toFile();
-        Files.delete(packageFile.toPath());
+        Files.deleteIfExists(packageFile.toPath());
         Files.copy(mTestContext.getResources().openRawResource(R.raw.ota_002_package),
                 packageFile.toPath());
         String url = "file://" + packageFile.getAbsolutePath();
@@ -68,7 +68,7 @@
         File outFile = Paths
                 .get(mTargetContext.getCacheDir().getAbsolutePath(), "care_map.txt")
                 .toFile();
-        Files.delete(outFile.toPath());
+        Files.deleteIfExists(outFile.toPath());
         // download a chunk of ota.zip
         FileDownloader downloader = new FileDownloader(url, 160, 8, outFile);
         downloader.download();