Android UCI engine update: Sting 8.1.ACH

Sting is a Stockfish derivative forked from v2.3.1 a long time ago and maintained by Marek Kwiatkowski.

I hope below build prepared by Alexei Chernakoff will perform much better than the last Android port of v7.3 by Aprijal in Rapidroid. I expect it to be around 3150 ELO. 

GET Sting 8.1.ACH for arm7

In case of trouble downloading from your PC, use your mobile device or refer to THIS POST.