fixed issue #797: handle audio focus in StageActivity
Merge pull request #975 from Catrobat/issue#797

fixed issue #797: handle audio focus in StageActivity
bricks, utils and layouts copied
modified files that could cause merge conflicts
testclasses copied
bugfix - wrong bitmask used
removed unused variable
trying to suppress hardcoded ip waring, using //nopmd
removed sprite parameter from led action
pull request #996 comments