small clean up, add missing xxxhdpi icon

app/src/main/java/net/bierbaumer/otp_authenticator/EncryptionHelper.java

@@ -88,8 +88,7 @@ public class EncryptionHelper {
         // Even if we just generated the key, always read it back to ensure we
         // can read it successfully.
         final byte[] wrapped = readFully(keyFile);
-        final SecretKey key = wrapper.unwrap(wrapped);
 
-        return key;
+        return wrapper.unwrap(wrapped);
     }
 }

app/src/main/java/net/bierbaumer/otp_authenticator/MyApplication.java

@@ -1,7 +1,6 @@
 package net.bierbaumer.otp_authenticator;
 
 import android.app.Application;
-import android.util.Log;
 
 public class MyApplication extends Application {
     @Override