add checkstyle and findbugs
add checkstyle and findbugs

brharrington/servo,fengshao0907/servo,dmuino/servo,entelesis/servo,ccortezb/servo,fengshao0907/servo,brharrington/servo,sensaid/servo,gorcz/servo,eonezhang/servo,entelesis/servo,ccortezb/servo,sensaid/servo,eonezhang/servo,Netflix/servo,rspieldenner/servo,dmuino/servo