Added scaled versions of checkeredbg.png to dp-specific drawable folders to prevent anti-aliasing
Deleted dp-independent version of checkeredbg.png
Merge pull request #161 from Catrobat/Issue154_TransparencyGrid_NoAntiAliasing

Issue154 transparency grid no anti aliasing
Implementation: @dladenhauf [DL]
Acceptance: @galstc05 [SG]