change recording format to aac with extension m4a
- refactored SoundRecorderTest: now waits for view change
- bugfix for startSensorListener, redundant calls caused runtime exception
- converted standard project audio files to aac
- important fix for testIfBrickParts Test. Eliminated Timing problems
Merge pull request #958 from Catrobat/823_Missing_MP3_Headers_New

fixes #823 missing mp3 headers