Guard use of console.warn for IE8
Guard use of console.warn for IE8

Fixes #151
rolandpoulter/radium,richardfickling/radium,Cottin/radium,jurgob/radium,clessg/radium,almost/radium,kof/radium,KenPowers/radium,namuol/radium-insert-rule,andyhite/radium,MicheleBertoli/radium,KenPowers/radium,moret/radium,FormidableLabs/radium,bencao/radium,bencao/radium,yetone/radium,clessg/radium,rolandpoulter/radium,haridusenadeera/radium,Cottin/radium,bobbyrenwick/radium,lexical-labs/radium,azazdeaz/radium,WillJHaggard/radium,dabbott/radium,haridusenadeera/radium,AnSavvides/radium,yetone/radium,azazdeaz/radium,nfl/radium,andyhite/radium,basarat/radium