PMD Warnings fixed.
(from 124 to 86)
Merge pull request #893 from Catrobat/PMDWarnings

PMDWarnings removed. Part 1 - Part 4
fixed PMDWarnings.
fixed PMDWarnings.
Merge pull request #899 from Catrobat/PMDWarningsPart7

removed PMDWarnings Part7
Merge pull request #900 from Catrobat/PMDWarningsPart6

removed PMDWarnings Part6
Merge branch 'master' into led_brick