chore(package): update babel-core to version 6.7.4
chore(package): update babel-core to version 6.7.4

http://greenkeeper.io/
linhanyang/keystone,ratecity/keystone,alobodig/keystone,jstockwin/keystone,Yaska/keystone,tony2cssc/keystone,brianjd/keystone,danielmahon/keystone,matthewstyers/keystone,pr1ntr/keystone,naustudio/keystone,naustudio/keystone,pswoodworth/keystone,sendyhalim/keystone,snowkeeper/keystone,sendyhalim/keystone,dvdcastro/keystone,Adam14Four/keystone,naustudio/keystone,matthewstyers/keystone,andrewlinfoot/keystone,suryagh/keystone,ratecity/keystone,andreufirefly/keystone,webteckie/keystone,frontyard/keystone,joerter/keystone,Tangcuyu/keystone,vokal/keystone,matthewstyers/keystone,andreufirefly/keystone,snowkeeper/keystone,frontyard/keystone,dryna/keystone-twoje-urodziny,danielmahon/keystone,pswoodworth/keystone,Tangcuyu/keystone,pr1ntr/keystone,ONode/keystone,matthieugayon/keystone,trentmillar/keystone,concoursbyappointment/keystoneRedux,rafmsou/keystone,trentmillar/keystone,andrewlinfoot/keystone,vokal/keystone,benkroeger/keystone,cermati/keystone,matthieugayon/keystone,brianjd/keystone,vokal/keystone,xyzteam2016/keystone,qwales1/keystone,ONode/keystone,jacargentina/keystone,everisARQ/keystone,jstockwin/keystone,wmertens/keystone,Yaska/keystone,tony2cssc/keystone,michaelerobertsjr/keystone,joerter/keystone,concoursbyappointment/keystoneRedux,dryna/keystone-twoje-urodziny,everisARQ/keystone,cermati/keystone,andrewlinfoot/keystone,Pop-Code/keystone,w01fgang/keystone,trentmillar/keystone,rafmsou/keystone,qwales1/keystone,michaelerobertsjr/keystone,wmertens/keystone,jacargentina/keystone,Adam14Four/keystone,xyzteam2016/keystone,suryagh/keystone,danielmahon/keystone,benkroeger/keystone,w01fgang/keystone,alobodig/keystone,Yaska/keystone,dvdcastro/keystone,benkroeger/keystone,webteckie/keystone,Pop-Code/keystone,frontyard/keystone