Test that file methods warn. Closes gh-909.
Test that file methods warn. Closes gh-909.

paladox/grunt,FeodorFitsner/grunt,q310550690/grunt,yonglehou/grunt,vladikoff/grunt,shama/grunt,pandeysoni/grunt,abraheem/grunt,eelve/grunt,lkiarest/grunt,thecc4re/gruntjs,yuhualingfeng/grunt,r14r-work/fork_grunt_master,zackexplosion/grunt,felixgrey/grunt,modulexcite/grunt,paulcbetts/grunt,youmyyou/grunt,goodeggs/grunt,yosiazwan/grunt,ThiagoGarciaAlves/grunt,imjerrybao/grunt,JaKXz/grunt,coldrye-collaboration/grunt,fscherwi/grunt,thejameskyle/grunt,Chhunlong/grunt,r14r/fork_grunt_master,IveWong/grunt,arosa81/grunt