sails teardown should handle SIGUSR2 kill signal
sails teardown should handle SIGUSR2 kill signal

runnig sails in development mode using nodemon can cause one extra grunt instance on every sails lift.

nodemon sends a SIGUSR2 kill signal to an app when it sees a file update.

this commit handles this kill signal and lowers sail gracefully.

ctartist621/sails,jianpingw/sails,haavardw/sails,jsisaev1/sails,winlolo/sails,hellowin/sails,adrianha/sails,hokkoo/sails,Josebaseba/sails,boarderdav/sails,cazulu/sails,pmq20/sails,kevinburke/sails,tjwebb/sails,alex-zhang/sails,antodoms/sails,balderdashy/sails,hokkoo/sails,antoniopol06/sails,mphasize/sails,t2013anurag/sails,curphey/sails,scippio/sails,konstantinzolotarev/sails,giano/sails,mauricionr/sails,Hanifb/sails,rlugojr/sails,marnusw/sails,Shyp/sails,EdisonSu768/sails,sunnycmf/sails,taogb/sails,dylannnn/sails,dbuentello/sails,apowers313/sails,jakutis/sails,JumpLink/sails,AnyPresence/sails,erkstruwe/sails,yangchuoxian/sails,togusafish/logikinc-_-sails,alexferreira/sails,yinhe007/sails,saronwei/sails,leedm777/sails,mnaughto/sails,janladaking/sails,saniko/soundcloud_mithril,rlugojr/sails,xjpro/sails-windows-associations,youprofit/sails,vip-git/sails,prssn/sails,anweiss/sails,Benew/sails,leobudima/sails,zand3rs/sails,jenalgit/sails,giano/sails,denismars/sails,calling/sails,shaunstanislaus/sails,saniko/soundcloud_mithril,artBrown/sails,krishnaglick/sails,metidia/sails,vip-git/sails,tempbottle/sails,corbanb/sails,wsaccaco/sails,justsml/sails,listepo/sails,harrissoerja/sails,baracudaengine/SailsUi,jianpingw/sails,Karnith/sails-for-gulp