Fix box_url to vagrant box on vagrantcloud.com.
Fix box_url to vagrant box on vagrantcloud.com.

openspending/spendb,johnjohndoe/spendb,USStateDept/FPA_Core,johnjohndoe/spendb,spendb/spendb,CivicVision/datahub,openspending/spendb,spendb/spendb,CivicVision/datahub,CivicVision/datahub,pudo/spendb,USStateDept/FPA_Core,pudo/spendb,spendb/spendb,johnjohndoe/spendb,nathanhilbert/FPA_Core,nathanhilbert/FPA_Core,USStateDept/FPA_Core,pudo/spendb,nathanhilbert/FPA_Core,openspending/spendb