Rewrite of Remote Smart Card Reader

- use material design
- use AsyncTask instead of Runnable for VPCDWorker to integrate with the
  App's lifecycle
- use a dedicated Preference Activity
- integrated zxing's QR code scanner
- use Snackbar instead of Toast
- capture debug messages in log instead of explicitly passing messages
- use reader mode only, breaks support of Android before kitkat

remote-reader/app/src/main/res/menu/menu_main.xml

@@ -0,0 +1,11 @@
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    tools:context="com.vsmartcard.remotesmartcardreader.app.MainActivity">
+
+    <item
+        android:id="@+id/action_settings"
+        android:orderInCategory="100"
+        android:title="@string/action_settings"
+        app:showAsAction="never" />
+</menu>