ACCUMULO-4089 Revert the checkstyle-plugin version
ACCUMULO-4089 Revert the checkstyle-plugin version

Version 2.15 doesn't work with out JDK6 limit on 1.6.x

dhutchis/accumulo,ctubbsii/accumulo,mikewalch/accumulo,lstav/accumulo,dhutchis/accumulo,mjwall/accumulo,ivakegg/accumulo,ctubbsii/accumulo,ivakegg/accumulo,keith-turner/accumulo,phrocker/accumulo-1,mikewalch/accumulo,adamjshook/accumulo,apache/accumulo,dhutchis/accumulo,apache/accumulo,adamjshook/accumulo,mikewalch/accumulo,lstav/accumulo,adamjshook/accumulo,dhutchis/accumulo,milleruntime/accumulo,apache/accumulo,adamjshook/accumulo,ivakegg/accumulo,lstav/accumulo,mikewalch/accumulo,mjwall/accumulo,ivakegg/accumulo,mjwall/accumulo,milleruntime/accumulo,ctubbsii/accumulo,adamjshook/accumulo,keith-turner/accumulo,phrocker/accumulo-1,adamjshook/accumulo,mikewalch/accumulo,adamjshook/accumulo,dhutchis/accumulo,ivakegg/accumulo,mjwall/accumulo,phrocker/accumulo-1,mikewalch/accumulo,ctubbsii/accumulo,phrocker/accumulo-1,lstav/accumulo,ivakegg/accumulo,milleruntime/accumulo,mikewalch/accumulo,dhutchis/accumulo,lstav/accumulo,apache/accumulo,phrocker/accumulo-1,adamjshook/accumulo,ctubbsii/accumulo,milleruntime/accumulo,lstav/accumulo,dhutchis/accumulo,keith-turner/accumulo,mjwall/accumulo,ivakegg/accumulo,mjwall/accumulo,apache/accumulo,phrocker/accumulo-1,dhutchis/accumulo,dhutchis/accumulo,keith-turner/accumulo,milleruntime/accumulo,ctubbsii/accumulo,adamjshook/accumulo,keith-turner/accumulo,ctubbsii/accumulo,mjwall/accumulo,keith-turner/accumulo,keith-turner/accumulo,mikewalch/accumulo,phrocker/accumulo-1,milleruntime/accumulo,apache/accumulo,apache/accumulo,milleruntime/accumulo,lstav/accumulo