[NGRINDER-49] Clean up checkstyle errors  - fix checkstyle.xml for compatibility with checkstyle maven plugin.
[NGRINDER-49] Clean up checkstyle errors 
- fix checkstyle.xml for compatibility with checkstyle maven plugin.
songeunwoo/ngrinder,songeunwoo/ngrinder,ropik/ngrinder,GwonGisoo/ngrinder,ropik/ngrinder,bwahn/ngrinder,nanpa83/ngrinder,nanpa83/ngrinder,songeunwoo/ngrinder,GwonGisoo/ngrinder,ropik/ngrinder,bwahn/ngrinder,bwahn/ngrinder,SRCB-CloudPart/ngrinder,SRCB-CloudPart/ngrinder,chengaomin/ngrinder,naver/ngrinder,GwonGisoo/ngrinder,naver/ngrinder,naver/ngrinder,chengaomin/ngrinder,SRCB-CloudPart/ngrinder,nanpa83/ngrinder,chengaomin/ngrinder,GwonGisoo/ngrinder,naver/ngrinder,chengaomin/ngrinder,songeunwoo/ngrinder,bwahn/ngrinder,nanpa83/ngrinder,bwahn/ngrinder,chengaomin/ngrinder,ropik/ngrinder,SRCB-CloudPart/ngrinder,naver/ngrinder,nanpa83/ngrinder,SRCB-CloudPart/ngrinder,GwonGisoo/ngrinder,songeunwoo/ngrinder