SMS Filter version 1.3

In my previous merge request, #238 (closed), version 1.2 didn't compile against android-8, like the metadata file claimed.

I apologize for it. I thought I had tested building it against android-8, and I just flat out didn't!
(It turned out I simply used a constant from android.os.Build.VERSION_CODES where I should've used the actual value rather than its alias, since the alias of course doesn't exist in earlier SDKs.)

I have fixed the issue, so the current code compiles against every target starting at android-8.

So here's, hopefully for a while, the last merge request for the SMS Filter application.

Thanks for your patience and vigilance, ;-)
Jelle Geerts